1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2019 */
6 /* Copyright (c) The Exim Maintainers 2020 - 2021 */
7 /* See the file NOTICE for conditions of use and distribution. */
9 /* Portions Copyright (c) The OpenSSL Project 1999 */
11 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
12 library. It is #included into the tls.c file when that library is used. The
13 code herein is based on a patch that was originally contributed by Steve
14 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
16 No cryptographic code is included in Exim. All this module does is to call
17 functions from the OpenSSL library. */
22 #include <openssl/lhash.h>
23 #include <openssl/ssl.h>
24 #include <openssl/err.h>
25 #include <openssl/rand.h>
26 #ifndef OPENSSL_NO_ECDH
27 # include <openssl/ec.h>
30 # include <openssl/ocsp.h>
38 # define EXIM_OCSP_SKEW_SECONDS (300L)
39 # define EXIM_OCSP_MAX_AGE (-1L)
42 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
43 # define EXIM_HAVE_OPENSSL_TLSEXT
45 #if OPENSSL_VERSION_NUMBER >= 0x00908000L
46 # define EXIM_HAVE_RSA_GENKEY_EX
48 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
49 # define EXIM_HAVE_OCSP_RESP_COUNT
50 # define OPENSSL_AUTO_SHA256
52 # define EXIM_HAVE_EPHEM_RSA_KEX
53 # define EXIM_HAVE_RAND_PSEUDO
55 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
56 # define EXIM_HAVE_SHA256
59 /* X509_check_host provides sane certificate hostname checking, but was added
60 to OpenSSL late, after other projects forked off the code-base. So in
61 addition to guarding against the base version number, beware that LibreSSL
62 does not (at this time) support this function.
64 If LibreSSL gains a different API, perhaps via libtls, then we'll probably
65 opt to disentangle and ask a LibreSSL user to provide glue for a third
66 crypto provider for libtls instead of continuing to tie the OpenSSL glue
67 into even twistier knots. If LibreSSL gains the same API, we can just
68 change this guard and punt the issue for a while longer. */
70 #ifndef LIBRESSL_VERSION_NUMBER
71 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
72 # define EXIM_HAVE_OPENSSL_CHECKHOST
73 # define EXIM_HAVE_OPENSSL_DH_BITS
74 # define EXIM_HAVE_OPENSSL_TLS_METHOD
75 # define EXIM_HAVE_OPENSSL_KEYLOG
76 # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
77 # define EXIM_HAVE_SESSION_TICKET
78 # define EXIM_HAVE_OPESSL_TRACE
79 # define EXIM_HAVE_OPESSL_GET0_SERIAL
81 # define EXIM_HAVE_OCSP
83 # define EXIM_HAVE_ALPN /* fail ret from hshake-cb is ignored by LibreSSL */
85 # define EXIM_NEED_OPENSSL_INIT
87 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
88 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
89 # define EXIM_HAVE_OPENSSL_CHECKHOST
93 #if LIBRESSL_VERSION_NUMBER >= 0x3040000fL
94 # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
97 #if !defined(LIBRESSL_VERSION_NUMBER) \
98 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
99 # if !defined(OPENSSL_NO_ECDH)
100 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
101 # define EXIM_HAVE_ECDH
103 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
104 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
109 #ifndef LIBRESSL_VERSION_NUMBER
110 # if OPENSSL_VERSION_NUMBER >= 0x010101000L
111 # define OPENSSL_HAVE_KEYLOG_CB
112 # define OPENSSL_HAVE_NUM_TICKETS
113 # define EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
115 # define OPENSSL_BAD_SRVR_OURCERT
119 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
120 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
121 # define DISABLE_OCSP
124 #ifndef DISABLE_TLS_RESUME
125 # if OPENSSL_VERSION_NUMBER < 0x0101010L
126 # error OpenSSL version too old for session-resumption
130 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
131 # include <openssl/x509v3.h>
134 #ifndef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
135 # ifndef EXIM_HAVE_OPENSSL_CIPHER_GET_ID
136 # define SSL_CIPHER_get_id(c) (c->id)
138 # ifndef MACRO_PREDEF
139 # include "tls-cipher-stdname.c"
143 /*************************************************
144 * OpenSSL option parse *
145 *************************************************/
147 typedef struct exim_openssl_option {
150 } exim_openssl_option;
151 /* We could use a macro to expand, but we need the ifdef and not all the
152 options document which version they were introduced in. Policylet: include
153 all options unless explicitly for DTLS, let the administrator choose which
156 This list is current as of:
159 XXX could we autobuild this list, as with predefined-macros?
160 Seems just parsing ssl.h for SSL_OP_.* would be enough (except to exclude DTLS).
161 Also allow a numeric literal?
163 static exim_openssl_option exim_openssl_options[] = {
164 /* KEEP SORTED ALPHABETICALLY! */
166 { US"all", (long) SSL_OP_ALL },
168 #ifdef SSL_OP_ALLOW_NO_DHE_KEX
169 { US"allow_no_dhe_kex", SSL_OP_ALLOW_NO_DHE_KEX },
171 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
172 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
174 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
175 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
177 #ifdef SSL_OP_CRYPTOPRO_TLSEXT_BUG
178 { US"cryptopro_tlsext_bug", SSL_OP_CRYPTOPRO_TLSEXT_BUG },
180 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
181 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
183 #ifdef SSL_OP_ENABLE_MIDDLEBOX_COMPAT
184 { US"enable_middlebox_compat", SSL_OP_ENABLE_MIDDLEBOX_COMPAT },
186 #ifdef SSL_OP_EPHEMERAL_RSA
187 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
189 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
190 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
192 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
193 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
195 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
196 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
198 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
199 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
201 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
202 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
204 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
205 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
207 #ifdef SSL_OP_NO_ANTI_REPLAY
208 { US"no_anti_replay", SSL_OP_NO_ANTI_REPLAY },
210 #ifdef SSL_OP_NO_COMPRESSION
211 { US"no_compression", SSL_OP_NO_COMPRESSION },
213 #ifdef SSL_OP_NO_ENCRYPT_THEN_MAC
214 { US"no_encrypt_then_mac", SSL_OP_NO_ENCRYPT_THEN_MAC },
216 #ifdef SSL_OP_NO_RENEGOTIATION
217 { US"no_renegotiation", SSL_OP_NO_RENEGOTIATION },
219 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
220 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
222 #ifdef SSL_OP_NO_SSLv2
223 { US"no_sslv2", SSL_OP_NO_SSLv2 },
225 #ifdef SSL_OP_NO_SSLv3
226 { US"no_sslv3", SSL_OP_NO_SSLv3 },
228 #ifdef SSL_OP_NO_TICKET
229 { US"no_ticket", SSL_OP_NO_TICKET },
231 #ifdef SSL_OP_NO_TLSv1
232 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
234 #ifdef SSL_OP_NO_TLSv1_1
235 # if OPENSSL_VERSION_NUMBER < 0x30000000L
236 # if SSL_OP_NO_TLSv1_1 == 0x00000400L
237 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
238 # warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
239 # define NO_SSL_OP_NO_TLSv1_1
242 # ifndef NO_SSL_OP_NO_TLSv1_1
243 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
246 #ifdef SSL_OP_NO_TLSv1_2
247 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
249 #ifdef SSL_OP_NO_TLSv1_3
250 { US"no_tlsv1_3", SSL_OP_NO_TLSv1_3 },
252 #ifdef SSL_OP_PRIORITIZE_CHACHA
253 { US"prioritize_chacha", SSL_OP_PRIORITIZE_CHACHA },
255 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
256 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
258 #ifdef SSL_OP_SINGLE_DH_USE
259 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
261 #ifdef SSL_OP_SINGLE_ECDH_USE
262 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
264 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
265 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
267 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
268 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
270 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
271 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
273 #ifdef SSL_OP_TLS_D5_BUG
274 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
276 #ifdef SSL_OP_TLS_ROLLBACK_BUG
277 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
279 #ifdef SSL_OP_TLSEXT_PADDING
280 { US"tlsext_padding", SSL_OP_TLSEXT_PADDING },
285 static int exim_openssl_options_size = nelem(exim_openssl_options);
286 static long init_options = 0;
295 for (struct exim_openssl_option * o = exim_openssl_options;
296 o < exim_openssl_options + nelem(exim_openssl_options); o++)
298 /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1
299 being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */
301 spf(buf, sizeof(buf), US"_OPT_OPENSSL_%T_X", o->name);
302 builtin_macro_create(buf);
305 # ifndef DISABLE_TLS_RESUME
306 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
308 # ifdef SSL_OP_NO_TLSv1_3
309 builtin_macro_create(US"_HAVE_TLS1_3");
311 # ifdef OPENSSL_BAD_SRVR_OURCERT
312 builtin_macro_create(US"_TLS_BAD_MULTICERT_IN_OURCERT");
314 # ifdef EXIM_HAVE_OCSP
315 builtin_macro_create(US"_HAVE_TLS_OCSP");
316 builtin_macro_create(US"_HAVE_TLS_OCSP_LIST");
318 # ifdef EXIM_HAVE_ALPN
319 builtin_macro_create(US"_HAVE_TLS_ALPN");
324 /******************************************************************************/
326 /* Structure for collecting random data for seeding. */
328 typedef struct randstuff {
333 /* Local static variables */
335 static BOOL client_verify_callback_called = FALSE;
336 static BOOL server_verify_callback_called = FALSE;
337 static const uschar *sid_ctx = US"exim";
339 /* We have three different contexts to care about.
341 Simple case: client, `client_ctx`
342 As a client, we can be doing a callout or cut-through delivery while receiving
343 a message. So we have a client context, which should have options initialised
344 from the SMTP Transport. We may also concurrently want to make TLS connections
345 to utility daemons, so client-contexts are allocated and passed around in call
346 args rather than using a gobal.
349 There are two cases: with and without ServerNameIndication from the client.
350 Given TLS SNI, we can be using different keys, certs and various other
351 configuration settings, because they're re-expanded with $tls_sni set. This
352 allows vhosting with TLS. This SNI is sent in the handshake.
353 A client might not send SNI, so we need a fallback, and an initial setup too.
354 So as a server, we start out using `server_ctx`.
355 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
356 `server_sni` from `server_ctx` and then initialise settings by re-expanding
364 } exim_openssl_client_tls_ctx;
367 /* static SSL_CTX *server_ctx = NULL; */
368 /* static SSL *server_ssl = NULL; */
370 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
371 static SSL_CTX *server_sni = NULL;
373 #ifdef EXIM_HAVE_ALPN
374 static BOOL server_seen_alpn = FALSE;
377 static char ssl_errstring[256];
379 static int ssl_session_timeout = 7200; /* Two hours */
380 static BOOL client_verify_optional = FALSE;
381 static BOOL server_verify_optional = FALSE;
383 static BOOL reexpand_tls_files_for_sni = FALSE;
386 typedef struct ocsp_resp {
387 struct ocsp_resp * next;
388 OCSP_RESPONSE * resp;
391 typedef struct exim_openssl_state {
392 exim_tlslib_state lib_state;
393 #define lib_ctx libdata0
394 #define lib_ssl libdata1
397 uschar * certificate;
401 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
405 const uschar *file_expanded;
406 ocsp_resplist *olist;
409 X509_STORE *verify_store; /* non-null if status requested */
410 BOOL verify_required;
415 /* these are cached from first expand */
416 uschar * server_cipher_list;
417 /* only passed down to tls_error: */
419 const uschar * verify_cert_hostnames;
420 #ifndef DISABLE_EVENT
421 uschar * event_action;
423 } exim_openssl_state_st;
425 /* should figure out a cleanup of API to handle state preserved per
426 implementation, for various reasons, which can be void * in the APIs.
427 For now, we hack around it. */
428 exim_openssl_state_st *client_static_state = NULL; /*XXX should not use static; multiple concurrent clients! */
429 exim_openssl_state_st state_server = {.is_server = TRUE};
432 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
437 static int tls_server_stapling_cb(SSL *s, void *arg);
442 /* Daemon-called, before every connection, key create/rotate */
443 #ifndef DISABLE_TLS_RESUME
444 static void tk_init(void);
445 static int tls_exdata_idx = -1;
449 tls_per_lib_daemon_tick(void)
451 #ifndef DISABLE_TLS_RESUME
456 /* Called once at daemon startup */
459 tls_per_lib_daemon_init(void)
461 tls_daemon_creds_reload();
465 /*************************************************
467 *************************************************/
469 /* Called from lots of places when errors occur before actually starting to do
470 the TLS handshake, that is, while the session is still in clear. Always returns
471 DEFER for a server and FAIL for a client so that most calls can use "return
472 tls_error(...)" to do this processing and then give an appropriate return. A
473 single function is used for both server and client, because it is called from
474 some shared functions.
477 prefix text to include in the logged error
478 host NULL if setting up a server;
479 the connected host if setting up a client
480 msg error message or NULL if we should ask OpenSSL
481 errstr pointer to output error message
483 Returns: OK/DEFER/FAIL
487 tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
491 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
492 msg = US ssl_errstring;
495 msg = string_sprintf("(%s): %s", prefix, msg);
496 DEBUG(D_tls) debug_printf("TLS error '%s'\n", msg);
497 if (errstr) *errstr = msg;
498 return host ? FAIL : DEFER;
503 /**************************************************
504 * General library initalisation *
505 **************************************************/
508 lib_rand_init(void * addr)
511 if (!RAND_status()) return TRUE;
513 gettimeofday(&r.tv, NULL);
515 RAND_seed(US (&r), sizeof(r));
516 RAND_seed(US big_buffer, big_buffer_size);
517 if (addr) RAND_seed(US addr, sizeof(addr));
519 return RAND_status();
524 tls_openssl_init(void)
526 static BOOL once = FALSE;
530 #ifdef EXIM_NEED_OPENSSL_INIT
531 SSL_load_error_strings(); /* basic set up */
532 OpenSSL_add_ssl_algorithms();
535 #if defined(EXIM_HAVE_SHA256) && !defined(OPENSSL_AUTO_SHA256)
536 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
537 list of available digests. */
538 EVP_add_digest(EVP_sha256());
541 (void) lib_rand_init(NULL);
542 (void) tls_openssl_options_parse(openssl_options, &init_options);
547 /*************************************************
548 * Initialize for DH *
549 *************************************************/
551 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
555 sctx The current SSL CTX (inbound or outbound)
556 dhparam DH parameter file or fixed parameter identity string
557 errstr error string pointer
559 Returns: TRUE if OK (nothing to set up, or setup worked)
563 init_dh(SSL_CTX * sctx, uschar * dhparam, uschar ** errstr)
566 #if OPENSSL_VERSION_NUMBER < 0x30000000L
575 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
578 if (!dhexpanded || !*dhexpanded)
579 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
580 else if (dhexpanded[0] == '/')
582 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
584 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
585 NULL, US strerror(errno), errstr);
591 if (Ustrcmp(dhexpanded, "none") == 0)
593 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
597 if (!(pem = std_dh_prime_named(dhexpanded)))
599 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
600 NULL, US strerror(errno), errstr);
603 bio = BIO_new_mem_buf(CS pem, -1);
607 #if OPENSSL_VERSION_NUMBER < 0x30000000L
608 dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)
610 pkey = PEM_read_bio_Parameters_ex(bio, NULL, NULL, NULL)
615 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
620 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
621 an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with 2236.
622 But older OpenSSL can only report in bytes (octets), not bits. If someone wants
623 to dance at the edge, then they can raise the limit or use current libraries. */
625 #if OPENSSL_VERSION_NUMBER < 0x30000000L
626 # ifdef EXIM_HAVE_OPENSSL_DH_BITS
627 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
628 This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
629 dh_bitsize = DH_bits(dh);
631 dh_bitsize = 8 * DH_size(dh);
634 dh_bitsize = EVP_PKEY_get_bits(pkey);
637 /* Even if it is larger, we silently return success rather than cause things to
638 fail out, so that a too-large DH will not knock out all TLS; it's a debatable
639 choice. Likewise for a failing attempt to set one. */
641 if (dh_bitsize <= tls_dh_max_bits)
644 #if OPENSSL_VERSION_NUMBER < 0x30000000L
645 SSL_CTX_set_tmp_dh(sctx, dh)
647 SSL_CTX_set0_tmp_dh_pkey(sctx, pkey)
651 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
652 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (D-H param setting '%s'): %s",
653 dhexpanded ? dhexpanded : US"default", ssl_errstring);
654 #if OPENSSL_VERSION_NUMBER >= 0x30000000L
655 /* EVP_PKEY_free(pkey); crashes */
660 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
661 dhexpanded ? dhexpanded : US"default", dh_bitsize);
665 debug_printf("dhparams '%s' %d bits, is > tls_dh_max_bits limit of %d\n",
666 dhexpanded ? dhexpanded : US"default", dh_bitsize, tls_dh_max_bits);
668 #if OPENSSL_VERSION_NUMBER < 0x30000000L
671 /* The EVP_PKEY ownership stays with the ctx; do not free it */
680 /*************************************************
681 * Initialize for ECDH *
682 *************************************************/
684 /* Load parameters for ECDH encryption. Server only.
686 For now, we stick to NIST P-256 because: it's simple and easy to configure;
687 it avoids any patent issues that might bite redistributors; despite events in
688 the news and concerns over curve choices, we're not cryptographers, we're not
689 pretending to be, and this is "good enough" to be better than no support,
690 protecting against most adversaries. Given another year or two, there might
691 be sufficient clarity about a "right" way forward to let us make an informed
692 decision, instead of a knee-jerk reaction.
694 Longer-term, we should look at supporting both various named curves and
695 external files generated with "openssl ecparam", much as we do for init_dh().
696 We should also support "none" as a value, to explicitly avoid initialisation.
701 sctx The current SSL CTX (inbound or outbound)
702 errstr error string pointer
704 Returns: TRUE if OK (nothing to set up, or setup worked)
708 init_ecdh(SSL_CTX * sctx, uschar ** errstr)
710 #ifdef OPENSSL_NO_ECDH
718 # ifndef EXIM_HAVE_ECDH
720 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
724 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
726 if (!exp_curve || !*exp_curve)
729 /* "auto" needs to be handled carefully.
730 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
731 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
732 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
733 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
734 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
736 if (Ustrcmp(exp_curve, "auto") == 0)
738 #if OPENSSL_VERSION_NUMBER < 0x10002000L
739 DEBUG(D_tls) debug_printf(
740 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
741 exp_curve = US"prime256v1";
743 # if defined SSL_CTRL_SET_ECDH_AUTO
744 DEBUG(D_tls) debug_printf(
745 "ECDH OpenSSL 1.0.2+: temp key parameter settings: autoselection\n");
746 SSL_CTX_set_ecdh_auto(sctx, 1);
749 DEBUG(D_tls) debug_printf(
750 "ECDH OpenSSL 1.1.0+: temp key parameter settings: default selection\n");
756 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
757 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
758 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
759 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
763 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
768 # if OPENSSL_VERSION_NUMBER < 0x30000000L
771 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
773 tls_error(US"Unable to create ec curve", NULL, NULL, errstr);
777 /* The "tmp" in the name here refers to setting a temporary key
778 not to the stability of the interface. */
780 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
781 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), NULL, NULL, errstr);
783 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
787 #else /* v 3.0.0 + */
789 if ((rv = SSL_CTX_set1_groups(sctx, &nid, 1)) == 0)
790 tls_error(string_sprintf("Error enabling '%s' group", exp_curve), NULL, NULL, errstr);
792 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' group\n", exp_curve);
798 # endif /*EXIM_HAVE_ECDH*/
799 #endif /*OPENSSL_NO_ECDH*/
804 /*************************************************
805 * Expand key and cert file specs *
806 *************************************************/
808 #if OPENSSL_VERSION_NUMBER < 0x30000000L
811 s SSL connection (not used)
815 Returns: pointer to generated key
819 rsa_callback(SSL *s, int export, int keylength)
822 #ifdef EXIM_HAVE_RSA_GENKEY_EX
823 BIGNUM *bn = BN_new();
826 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
828 # ifdef EXIM_HAVE_RSA_GENKEY_EX
829 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
830 || !(rsa_key = RSA_new())
831 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
834 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
838 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
839 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
845 #endif /* pre-3.0.0 */
849 /* Create and install a selfsigned certificate, for use in server mode */
850 /*XXX we could arrange to call this during prelo for a null tls_certificate option.
851 The normal cache inval + relo will suffice.
852 Just need a timer for inval. */
855 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
862 DEBUG(D_tls) debug_printf("TLS: generating selfsigned server cert\n");
863 where = US"allocating pkey";
864 if (!(pkey = EVP_PKEY_new()))
867 where = US"allocating cert";
868 if (!(x509 = X509_new()))
871 where = US"generating pkey";
872 #if OPENSSL_VERSION_NUMBER < 0x30000000L
875 if (!(rsa = rsa_callback(NULL, 0, 2048)))
878 where = US"assigning pkey";
879 if (!EVP_PKEY_assign_RSA(pkey, rsa))
883 pkey = EVP_RSA_gen(2048);
886 X509_set_version(x509, 2); /* N+1 - version 3 */
887 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
888 X509_gmtime_adj(X509_get_notBefore(x509), 0);
889 X509_gmtime_adj(X509_get_notAfter(x509), (long)2 * 60 * 60); /* 2 hour */
890 X509_set_pubkey(x509, pkey);
892 name = X509_get_subject_name(x509);
893 X509_NAME_add_entry_by_txt(name, "C",
894 MBSTRING_ASC, CUS "UK", -1, -1, 0);
895 X509_NAME_add_entry_by_txt(name, "O",
896 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
897 X509_NAME_add_entry_by_txt(name, "CN",
898 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
899 X509_set_issuer_name(x509, name);
901 where = US"signing cert";
902 if (!X509_sign(x509, pkey, EVP_md5()))
905 where = US"installing selfsign cert";
906 if (!SSL_CTX_use_certificate(sctx, x509))
909 where = US"installing selfsign key";
910 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
916 (void) tls_error(where, NULL, NULL, errstr);
917 if (x509) X509_free(x509);
918 if (pkey) EVP_PKEY_free(pkey);
928 /*************************************************
929 * Information callback *
930 *************************************************/
932 /* The SSL library functions call this from time to time to indicate what they
933 are doing. We copy the string to the debugging output when TLS debugging has
945 info_callback(SSL *s, int where, int ret)
951 if (where & SSL_ST_CONNECT)
952 str = US"SSL_connect";
953 else if (where & SSL_ST_ACCEPT)
954 str = US"SSL_accept";
956 str = US"SSL info (undefined)";
958 if (where & SSL_CB_LOOP)
959 debug_printf("%s: %s\n", str, SSL_state_string_long(s));
960 else if (where & SSL_CB_ALERT)
961 debug_printf("SSL3 alert %s:%s:%s\n",
962 str = where & SSL_CB_READ ? US"read" : US"write",
963 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
964 else if (where & SSL_CB_EXIT)
967 debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s));
969 debug_printf("%s: error in %s\n", str, SSL_state_string_long(s));
971 else if (where & SSL_CB_HANDSHAKE_START)
972 debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s));
973 else if (where & SSL_CB_HANDSHAKE_DONE)
974 debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s));
978 #ifdef OPENSSL_HAVE_KEYLOG_CB
980 keylog_callback(const SSL *ssl, const char *line)
984 DEBUG(D_tls) debug_printf("%.200s\n", line);
985 if (!(filename = getenv("SSLKEYLOGFILE"))) return;
986 if (!(fp = fopen(filename, "a"))) return;
987 fprintf(fp, "%s\n", line);
996 #ifndef DISABLE_EVENT
998 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
999 BOOL *calledp, const BOOL *optionalp, const uschar * what)
1005 ev = tlsp == &tls_out ? client_static_state->event_action : event_action;
1008 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
1009 old_cert = tlsp->peercert;
1010 tlsp->peercert = X509_dup(cert);
1011 /* NB we do not bother setting peerdn */
1012 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
1014 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
1015 "depth=%d cert=%s: %s",
1016 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1017 what, depth, dn, yield);
1021 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
1022 return 1; /* reject (leaving peercert set) */
1024 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
1025 "(host in tls_try_verify_hosts)\n");
1026 tlsp->verify_override = TRUE;
1028 X509_free(tlsp->peercert);
1029 tlsp->peercert = old_cert;
1035 /*************************************************
1036 * Callback for verification *
1037 *************************************************/
1039 /* The SSL library does certificate verification if set up to do so. This
1040 callback has the current yes/no state is in "state". If verification succeeded,
1041 we set the certificate-verified flag. If verification failed, what happens
1042 depends on whether the client is required to present a verifiable certificate
1045 If verification is optional, we change the state to yes, but still log the
1046 verification error. For some reason (it really would help to have proper
1047 documentation of OpenSSL), this callback function then gets called again, this
1048 time with state = 1. We must take care not to set the private verified flag on
1049 the second time through.
1051 Note: this function is not called if the client fails to present a certificate
1052 when asked. We get here only if a certificate has been received. Handling of
1053 optional verification for this case is done when requesting SSL to verify, by
1054 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
1056 May be called multiple times for different issues with a certificate, even
1057 for a given "depth" in the certificate chain.
1060 preverify_ok current yes/no state as 1/0
1061 x509ctx certificate information.
1062 tlsp per-direction (client vs. server) support data
1063 calledp has-been-called flag
1064 optionalp verification-is-optional flag
1066 Returns: 0 if verification should fail, otherwise 1
1070 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
1071 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
1073 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1074 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1077 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1079 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1080 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1081 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1084 dn[sizeof(dn)-1] = '\0';
1086 tlsp->verify_override = FALSE;
1087 if (preverify_ok == 0)
1089 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
1090 *verify_mode, sender_host_address)
1092 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
1093 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1095 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
1099 if (!tlsp->peercert)
1100 tlsp->peercert = X509_dup(cert); /* record failing cert */
1101 return 0; /* reject */
1103 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
1104 "tls_try_verify_hosts)\n");
1105 tlsp->verify_override = TRUE;
1108 else if (depth != 0)
1110 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
1111 #ifndef DISABLE_OCSP
1112 if (tlsp == &tls_out && client_static_state->u_ocsp.client.verify_store)
1113 { /* client, wanting stapling */
1114 /* Add the server cert's signing chain as the one
1115 for the verification of the OCSP stapled information. */
1117 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1120 sk_X509_push(client_static_state->verify_stack, cert);
1123 #ifndef DISABLE_EVENT
1124 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1125 return 0; /* reject, with peercert set */
1130 const uschar * verify_cert_hostnames;
1132 if ( tlsp == &tls_out
1133 && ((verify_cert_hostnames = client_static_state->verify_cert_hostnames)))
1134 /* client, wanting hostname check */
1137 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
1138 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1139 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
1141 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
1142 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
1145 const uschar * list = verify_cert_hostnames;
1148 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
1149 if ((rc = X509_check_host(cert, CCS name, 0,
1150 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
1151 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
1156 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1157 tlsp == &tls_out ? deliver_host_address : sender_host_address);
1164 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
1167 uschar * extra = verify_mode
1168 ? string_sprintf(" (during %c-verify for [%s])",
1169 *verify_mode, sender_host_address)
1171 log_write(0, LOG_MAIN,
1172 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
1173 tlsp == &tls_out ? deliver_host_address : sender_host_address,
1174 extra, dn, verify_cert_hostnames);
1178 if (!tlsp->peercert)
1179 tlsp->peercert = X509_dup(cert); /* record failing cert */
1180 return 0; /* reject */
1182 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
1183 "tls_try_verify_hosts)\n");
1184 tlsp->verify_override = TRUE;
1188 #ifndef DISABLE_EVENT
1189 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
1190 return 0; /* reject, with peercert set */
1193 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
1194 *calledp ? "" : " authenticated", dn);
1198 return 1; /* accept, at least for this level */
1202 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
1204 return verify_callback(preverify_ok, x509ctx, &tls_out,
1205 &client_verify_callback_called, &client_verify_optional);
1209 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
1211 return verify_callback(preverify_ok, x509ctx, &tls_in,
1212 &server_verify_callback_called, &server_verify_optional);
1218 /* This gets called *by* the dane library verify callback, which interposes
1222 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
1224 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
1226 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
1227 #ifndef DISABLE_EVENT
1228 BOOL dummy_called, optional = FALSE;
1231 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
1233 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
1234 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
1235 deliver_host_address);
1238 dn[sizeof(dn)-1] = '\0';
1240 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
1241 preverify_ok ? "ok":"BAD", depth, dn);
1243 #ifndef DISABLE_EVENT
1244 if (verify_event(&tls_out, cert, depth, dn,
1245 &dummy_called, &optional, US"DANE"))
1246 return 0; /* reject, with peercert set */
1249 if (preverify_ok == 1)
1251 tls_out.dane_verified = TRUE;
1252 #ifndef DISABLE_OCSP
1253 if (client_static_state->u_ocsp.client.verify_store)
1254 { /* client, wanting stapling */
1255 /* Add the server cert's signing chain as the one
1256 for the verification of the OCSP stapled information. */
1258 if (!X509_STORE_add_cert(client_static_state->u_ocsp.client.verify_store,
1261 sk_X509_push(client_static_state->verify_stack, cert);
1267 int err = X509_STORE_CTX_get_error(x509ctx);
1269 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
1270 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
1273 return preverify_ok;
1276 #endif /*SUPPORT_DANE*/
1279 #ifndef DISABLE_OCSP
1280 /*************************************************
1281 * Load OCSP information into state *
1282 *************************************************/
1283 /* Called to load the server OCSP response from the given file into memory, once
1284 caller has determined this is needed. Checks validity. Debugs a message
1287 ASSUMES: single response, for single cert.
1290 state various parts of session state
1291 filename the filename putatively holding an OCSP response
1292 is_pem file is PEM format; otherwise is DER
1296 ocsp_load_response(exim_openssl_state_st * state, const uschar * filename,
1300 OCSP_RESPONSE * resp;
1301 OCSP_BASICRESP * basic_response;
1302 OCSP_SINGLERESP * single_response;
1303 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1304 STACK_OF(X509) * sk;
1305 unsigned long verify_flags;
1306 int status, reason, i;
1309 debug_printf("tls_ocsp_file (%s) '%s'\n", is_pem ? "PEM" : "DER", filename);
1311 if (!filename || !*filename) return;
1314 if (!(bio = BIO_new_file(CS filename, "rb")))
1316 log_write(0, LOG_MAIN|LOG_PANIC,
1317 "Failed to open OCSP response file \"%s\": %.100s",
1318 filename, ERR_reason_error_string(ERR_get_error()));
1324 uschar * data, * freep;
1327 if (!PEM_read_bio(bio, &dummy, &dummy, &data, &len))
1329 log_write(0, LOG_MAIN|LOG_PANIC, "Failed to read PEM file \"%s\": %.100s",
1330 filename, ERR_reason_error_string(ERR_get_error()));
1334 resp = d2i_OCSP_RESPONSE(NULL, CUSS &data, len);
1335 OPENSSL_free(freep);
1338 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1343 log_write(0, LOG_MAIN|LOG_PANIC, "Error reading OCSP response from \"%s\": %s",
1344 filename, ERR_reason_error_string(ERR_get_error()));
1348 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1350 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1351 OCSP_response_status_str(status), status);
1357 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1358 OCSP_RESPONSE_print(bp, resp, 0); /* extreme debug: stapling content */
1363 if (!(basic_response = OCSP_response_get1_basic(resp)))
1366 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1370 sk = state->verify_stack;
1371 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1373 /* May need to expose ability to adjust those flags?
1374 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1375 OCSP_TRUSTOTHER OCSP_NOINTERN */
1377 /* This does a full verify on the OCSP proof before we load it for serving
1378 up; possibly overkill - just date-checks might be nice enough.
1380 OCSP_basic_verify takes a "store" arg, but does not
1381 use it for the chain verification, which is all we do
1382 when OCSP_NOVERIFY is set. The content from the wire
1383 "basic_response" and a cert-stack "sk" are all that is used.
1385 We have a stack, loaded in setup_certs() if tls_verify_certificates
1386 was a file (not a directory, or "system"). It is unfortunate we
1387 cannot used the connection context store, as that would neatly
1388 handle the "system" case too, but there seems to be no library
1389 function for getting a stack from a store.
1390 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1391 We do not free the stack since it could be needed a second time for
1394 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1395 be a public interface into the OpenSSL library (there's no manual entry) -
1396 But what with? We also use OCSP_basic_verify in the client stapling callback.
1397 And there we NEED it; we must verify that status... unless the
1398 library does it for us anyway? */
1400 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1404 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1405 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1410 /* Here's the simplifying assumption: there's only one response, for the
1411 one certificate we use, and nothing for anything else in a chain. If this
1412 proves false, we need to extract a cert id from our issued cert
1413 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1414 right cert in the stack and then calls OCSP_single_get0_status()).
1416 I'm hoping to avoid reworking a bunch more of how we handle state here.
1418 XXX that will change when we add support for (TLS1.3) whole-chain stapling
1421 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1424 debug_printf("Unable to get first response from OCSP basic response.\n");
1428 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1429 if (status != V_OCSP_CERTSTATUS_GOOD)
1431 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1432 OCSP_cert_status_str(status), status,
1433 OCSP_crl_reason_str(reason), reason);
1437 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1439 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1444 /* Add the resp to the list used by tls_server_stapling_cb() */
1446 ocsp_resplist ** op = &state->u_ocsp.server.olist, * oentry;
1447 while (oentry = *op)
1449 *op = oentry = store_get(sizeof(ocsp_resplist), FALSE);
1450 oentry->next = NULL;
1451 oentry->resp = resp;
1456 if (f.running_in_test_harness)
1458 extern char ** environ;
1459 if (environ) for (uschar ** p = USS environ; *p; p++)
1460 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1462 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1463 goto supply_response;
1471 ocsp_free_response_list(exim_openssl_state_st * cbinfo)
1473 for (ocsp_resplist * olist = cbinfo->u_ocsp.server.olist; olist;
1474 olist = olist->next)
1475 OCSP_RESPONSE_free(olist->resp);
1476 cbinfo->u_ocsp.server.olist = NULL;
1478 #endif /*!DISABLE_OCSP*/
1485 tls_add_certfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1488 DEBUG(D_tls) debug_printf("tls_certificate file '%s'\n", file);
1489 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1490 return tls_error(string_sprintf(
1491 "SSL_CTX_use_certificate_chain_file file=%s", file),
1492 cbinfo->host, NULL, errstr);
1497 tls_add_pkeyfile(SSL_CTX * sctx, exim_openssl_state_st * cbinfo, uschar * file,
1500 DEBUG(D_tls) debug_printf("tls_privatekey file '%s'\n", file);
1501 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1502 return tls_error(string_sprintf(
1503 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1510 /* Called once during tls_init and possibly again during TLS setup, for a
1511 new context, if Server Name Indication was used and tls_sni was seen in
1512 the certificate string.
1515 sctx the SSL_CTX* to update
1516 state various parts of session state
1517 errstr error string pointer
1519 Returns: OK/DEFER/FAIL
1523 tls_expand_session_files(SSL_CTX * sctx, exim_openssl_state_st * state,
1528 if (!state->certificate)
1530 if (!state->is_server) /* client */
1533 if (tls_install_selfsign(sctx, errstr) != OK)
1540 if ( !reexpand_tls_files_for_sni
1541 && ( Ustrstr(state->certificate, US"tls_sni")
1542 || Ustrstr(state->certificate, US"tls_in_sni")
1543 || Ustrstr(state->certificate, US"tls_out_sni")
1545 reexpand_tls_files_for_sni = TRUE;
1547 if (!expand_check(state->certificate, US"tls_certificate", &expanded, errstr))
1551 if (state->is_server)
1553 const uschar * file_list = expanded;
1556 #ifndef DISABLE_OCSP
1557 const uschar * olist = state->u_ocsp.server.file;
1560 BOOL fmt_pem = FALSE;
1563 if (!expand_check(olist, US"tls_ocsp_file", USS &olist, errstr))
1565 if (olist && !*olist)
1568 if ( state->u_ocsp.server.file_expanded && olist
1569 && (Ustrcmp(olist, state->u_ocsp.server.file_expanded) == 0))
1571 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1576 ocsp_free_response_list(state);
1577 state->u_ocsp.server.file_expanded = olist;
1581 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1583 if ((err = tls_add_certfile(sctx, state, file, errstr)))
1586 #ifndef DISABLE_OCSP
1588 if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1590 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1595 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1600 ocsp_load_response(state, ofile, fmt_pem);
1603 DEBUG(D_tls) debug_printf("ran out of ocsp file list\n");
1607 else /* would there ever be a need for multiple client certs? */
1608 if ((err = tls_add_certfile(sctx, state, expanded, errstr)))
1611 if ( state->privatekey
1612 && !expand_check(state->privatekey, US"tls_privatekey", &expanded, errstr))
1615 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1616 of the expansion is an empty string, ignore it also, and assume the private
1617 key is in the same file as the certificate. */
1619 if (expanded && *expanded)
1620 if (state->is_server)
1622 const uschar * file_list = expanded;
1626 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1627 if ((err = tls_add_pkeyfile(sctx, state, file, errstr)))
1630 else /* would there ever be a need for multiple client certs? */
1631 if ((err = tls_add_pkeyfile(sctx, state, expanded, errstr)))
1641 /**************************************************
1642 * One-time init credentials for server and client *
1643 **************************************************/
1646 normalise_ciphers(uschar ** ciphers, const uschar * pre_expansion_ciphers)
1648 uschar * s = *ciphers;
1650 if (!s || !Ustrchr(s, '_')) return; /* no change needed */
1652 if (s == pre_expansion_ciphers)
1653 s = string_copy(s); /* get writable copy */
1655 for (uschar * t = s; *t; t++) if (*t == '_') *t = '-';
1660 server_load_ciphers(SSL_CTX * ctx, exim_openssl_state_st * state,
1661 uschar * ciphers, uschar ** errstr)
1663 DEBUG(D_tls) debug_printf("required ciphers: %s\n", ciphers);
1664 if (!SSL_CTX_set_cipher_list(ctx, CS ciphers))
1665 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
1666 state->server_cipher_list = ciphers;
1673 lib_ctx_new(SSL_CTX ** ctxp, host_item * host, uschar ** errstr)
1676 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1677 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1679 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1681 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1683 /* Set up the information callback, which outputs if debugging is at a suitable
1688 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1689 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1690 /* this needs a debug build of OpenSSL */
1691 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
1693 #ifdef OPENSSL_HAVE_KEYLOG_CB
1694 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
1698 /* Automatically re-try reads/writes after renegotiation. */
1699 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1706 tls_server_creds_init(void)
1709 uschar * dummy_errstr;
1710 unsigned lifetime = 0;
1714 state_server.lib_state = null_tls_preload;
1716 if (lib_ctx_new(&ctx, NULL, &dummy_errstr) != OK)
1718 state_server.lib_state.lib_ctx = ctx;
1720 /* Preload DH params and EC curve */
1722 if (opt_unset_or_noexpand(tls_dhparam))
1724 DEBUG(D_tls) debug_printf("TLS: preloading DH params for server\n");
1725 if (init_dh(ctx, tls_dhparam, &dummy_errstr))
1726 state_server.lib_state.dh = TRUE;
1729 DEBUG(D_tls) debug_printf("TLS: not preloading DH params for server\n");
1730 if (opt_unset_or_noexpand(tls_eccurve))
1732 DEBUG(D_tls) debug_printf("TLS: preloading ECDH curve for server\n");
1733 if (init_ecdh(ctx, &dummy_errstr))
1734 state_server.lib_state.ecdh = TRUE;
1737 DEBUG(D_tls) debug_printf("TLS: not preloading ECDH curve for server\n");
1739 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1740 /* If we can, preload the server-side cert, key and ocsp */
1742 if ( opt_set_and_noexpand(tls_certificate)
1743 # ifndef DISABLE_OCSP
1744 && opt_unset_or_noexpand(tls_ocsp_file)
1746 && opt_unset_or_noexpand(tls_privatekey))
1748 /* Set watches on the filenames. The implementation does de-duplication
1749 so we can just blindly do them all. */
1751 if ( tls_set_watch(tls_certificate, TRUE)
1752 # ifndef DISABLE_OCSP
1753 && tls_set_watch(tls_ocsp_file, TRUE)
1755 && tls_set_watch(tls_privatekey, TRUE))
1757 state_server.certificate = tls_certificate;
1758 state_server.privatekey = tls_privatekey;
1759 #ifndef DISABLE_OCSP
1760 state_server.u_ocsp.server.file = tls_ocsp_file;
1763 DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
1764 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1765 state_server.lib_state.conn_certs = TRUE;
1768 else if ( !tls_certificate && !tls_privatekey
1769 # ifndef DISABLE_OCSP
1773 { /* Generate & preload a selfsigned cert. No files to watch. */
1774 if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
1776 state_server.lib_state.conn_certs = TRUE;
1777 lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
1781 DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
1784 /* If we can, preload the Authorities for checking client certs against.
1785 Actual choice to do verify is made (tls_{,try_}verify_hosts)
1786 at TLS conn startup */
1788 if ( opt_set_and_noexpand(tls_verify_certificates)
1789 && opt_unset_or_noexpand(tls_crl))
1791 /* Watch the default dir also as they are always included */
1793 if ( tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1794 && tls_set_watch(tls_verify_certificates, FALSE)
1795 && tls_set_watch(tls_crl, FALSE))
1797 DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
1799 if (setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, &dummy_errstr)
1801 state_server.lib_state.cabundle = TRUE;
1805 DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
1806 #endif /* EXIM_HAVE_INOTIFY */
1809 /* If we can, preload the ciphers control string */
1811 if (opt_set_and_noexpand(tls_require_ciphers))
1813 DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server\n");
1814 normalise_ciphers(&tls_require_ciphers, tls_require_ciphers);
1815 if (server_load_ciphers(ctx, &state_server, tls_require_ciphers,
1816 &dummy_errstr) == OK)
1817 state_server.lib_state.pri_string = TRUE;
1820 DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
1827 /* Preload whatever creds are static, onto a transport. The client can then
1828 just copy the pointer as it starts up.
1829 Called from the daemon after a cache-invalidate with watch set; called from
1830 a queue-run startup with watch clear. */
1833 tls_client_creds_init(transport_instance * t, BOOL watch)
1835 smtp_transport_options_block * ob = t->options_block;
1836 exim_openssl_state_st tpt_dummy_state;
1837 host_item * dummy_host = (host_item *)1;
1838 uschar * dummy_errstr;
1843 ob->tls_preload = null_tls_preload;
1844 if (lib_ctx_new(&ctx, dummy_host, &dummy_errstr) != OK)
1846 ob->tls_preload.lib_ctx = ctx;
1848 tpt_dummy_state.lib_state = ob->tls_preload;
1850 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1851 if ( opt_set_and_noexpand(ob->tls_certificate)
1852 && opt_unset_or_noexpand(ob->tls_privatekey))
1855 || ( tls_set_watch(ob->tls_certificate, FALSE)
1856 && tls_set_watch(ob->tls_privatekey, FALSE)
1859 uschar * pkey = ob->tls_privatekey;
1862 debug_printf("TLS: preloading client certs for transport '%s'\n",t->name);
1864 if ( tls_add_certfile(ctx, &tpt_dummy_state, ob->tls_certificate,
1866 && tls_add_pkeyfile(ctx, &tpt_dummy_state,
1867 pkey ? pkey : ob->tls_certificate,
1870 ob->tls_preload.conn_certs = TRUE;
1875 debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
1878 if ( opt_set_and_noexpand(ob->tls_verify_certificates)
1879 && opt_unset_or_noexpand(ob->tls_crl))
1882 || tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
1883 && tls_set_watch(ob->tls_verify_certificates, FALSE)
1884 && tls_set_watch(ob->tls_crl, FALSE)
1888 debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
1890 if (setup_certs(ctx, ob->tls_verify_certificates,
1891 ob->tls_crl, dummy_host, &dummy_errstr) == OK)
1892 ob->tls_preload.cabundle = TRUE;
1897 debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
1899 #endif /*EXIM_HAVE_INOTIFY*/
1903 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
1904 /* Invalidate the creds cached, by dropping the current ones.
1905 Call when we notice one of the source files has changed. */
1908 tls_server_creds_invalidate(void)
1910 SSL_CTX_free(state_server.lib_state.lib_ctx);
1911 state_server.lib_state = null_tls_preload;
1916 tls_client_creds_invalidate(transport_instance * t)
1918 smtp_transport_options_block * ob = t->options_block;
1919 SSL_CTX_free(ob->tls_preload.lib_ctx);
1920 ob->tls_preload = null_tls_preload;
1926 tls_server_creds_invalidate(void)
1930 tls_client_creds_invalidate(transport_instance * t)
1933 #endif /*EXIM_HAVE_INOTIFY*/
1937 #ifndef DISABLE_OCSP
1939 x509_store_dump_cert_s_names(X509_STORE * store)
1941 STACK_OF(X509_OBJECT) * roots= store->objs;
1942 static uschar name[256];
1944 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
1946 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
1947 if(tmp_obj->type == X509_LU_X509)
1949 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
1950 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
1952 name[sizeof(name)-1] = '\0';
1953 debug_printf(" %s\n", name);
1962 #ifndef DISABLE_TLS_RESUME
1963 /* Manage the keysets used for encrypting the session tickets, on the server. */
1965 typedef struct { /* Session ticket encryption key */
1968 const EVP_CIPHER * aes_cipher;
1969 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
1970 # if OPENSSL_VERSION_NUMBER < 0x30000000L
1971 const EVP_MD * hmac_hash;
1973 const uschar * hmac_hashname;
1975 uschar hmac_key[16];
1980 static exim_stek exim_tk; /* current key */
1981 static exim_stek exim_tk_old; /* previous key */
1986 time_t t = time(NULL);
1988 if (exim_tk.name[0])
1990 if (exim_tk.renew >= t) return;
1991 exim_tk_old = exim_tk;
1994 if (f.running_in_test_harness) ssl_session_timeout = 6;
1996 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
1997 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
1998 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
1999 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
2001 exim_tk.name[0] = 'E';
2002 exim_tk.aes_cipher = EVP_aes_256_cbc();
2003 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2004 exim_tk.hmac_hash = EVP_sha256();
2006 exim_tk.hmac_hashname = US "sha256";
2008 exim_tk.expire = t + ssl_session_timeout;
2009 exim_tk.renew = t + ssl_session_timeout/2;
2015 if (!exim_tk.name[0]) return NULL;
2020 tk_find(const uschar * name)
2022 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
2023 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
2030 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2038 /*XXX will want these dependent on the ssl session strength */
2039 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2040 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
2041 key->hmac_hash, NULL);
2044 OSSL_PARAM params[3];
2045 uschar * hk = string_copy(key->hmac_hashname); /* need nonconst */
2046 params[0] = OSSL_PARAM_construct_octet_string("key", key->hmac_key, sizeof(key->hmac_key));
2047 params[1] = OSSL_PARAM_construct_utf8_string("digest", CS hk, 0);
2048 params[2] = OSSL_PARAM_construct_end();
2049 if (EVP_MAC_CTX_set_params(hctx, params) == 0)
2051 DEBUG(D_tls) debug_printf("EVP_MAC_CTX_set_params: %s\n",
2052 ERR_reason_error_string(ERR_get_error()));
2053 return 0; /* error in mac initialisation */
2060 /* Callback for session tickets, on server */
2062 ticket_key_callback(SSL * ssl, uschar key_name[16],
2063 uschar * iv, EVP_CIPHER_CTX * c_ctx,
2064 # if OPENSSL_VERSION_NUMBER < 0x30000000L
2071 tls_support * tlsp = state_server.tlsp;
2076 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
2077 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2079 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
2080 return -1; /* insufficient random */
2082 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
2083 return 0; /* key couldn't be created */
2084 memcpy(key_name, key->name, 16);
2085 DEBUG(D_tls) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - time(NULL));
2087 if (tk_hmac_init(hctx, key) == 0) return 0;
2088 EVP_EncryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2090 DEBUG(D_tls) debug_printf("ticket created\n");
2095 time_t now = time(NULL);
2097 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
2098 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2100 if (!(key = tk_find(key_name)) || key->expire < now)
2104 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
2105 if (key) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - now);
2110 if (tk_hmac_init(hctx, key) == 0) return 0;
2111 EVP_DecryptInit_ex(c_ctx, key->aes_cipher, NULL, key->aes_key, iv);
2113 DEBUG(D_tls) debug_printf("ticket usable, STEK expire " TIME_T_FMT "\n", key->expire - now);
2115 /* The ticket lifetime and renewal are the same as the STEK lifetime and
2116 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
2117 be better. To do that we'd have to encode ticket lifetime in the name as
2118 we don't yet see the restored session. Could check posthandshake for TLS1.3
2119 and trigger a new ticket then, but cannot do that for TLS1.2 */
2120 return key->renew < now ? 2 : 1;
2123 #endif /* !DISABLE_TLS_RESUME */
2128 setup_cert_verify(SSL_CTX * ctx, BOOL optional,
2129 int (*cert_vfy_cb)(int, X509_STORE_CTX *))
2131 /* If verification is optional, don't fail if no certificate */
2133 SSL_CTX_set_verify(ctx,
2134 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2139 /*************************************************
2140 * Callback to handle SNI *
2141 *************************************************/
2143 /* Called when acting as server during the TLS session setup if a Server Name
2144 Indication extension was sent by the client.
2146 API documentation is OpenSSL s_server.c implementation.
2149 s SSL* of the current session
2150 ad unknown (part of OpenSSL API) (unused)
2151 arg Callback of "our" registered data
2153 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
2155 XXX might need to change to using ClientHello callback,
2156 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
2159 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2161 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
2163 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
2164 exim_openssl_state_st *state = (exim_openssl_state_st *) arg;
2166 int old_pool = store_pool;
2167 uschar * dummy_errstr;
2170 return SSL_TLSEXT_ERR_OK;
2172 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
2173 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
2175 /* Make the extension value available for expansion */
2176 store_pool = POOL_PERM;
2177 tls_in.sni = string_copy_taint(US servername, TRUE);
2178 store_pool = old_pool;
2180 if (!reexpand_tls_files_for_sni)
2181 return SSL_TLSEXT_ERR_OK;
2183 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
2184 not confident that memcpy wouldn't break some internal reference counting.
2185 Especially since there's a references struct member, which would be off. */
2187 if (lib_ctx_new(&server_sni, NULL, &dummy_errstr) != OK)
2190 /* Not sure how many of these are actually needed, since SSL object
2191 already exists. Might even need this selfsame callback, for reneg? */
2194 SSL_CTX * ctx = state_server.lib_state.lib_ctx;
2195 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(ctx));
2196 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(ctx));
2197 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(ctx));
2198 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(ctx));
2199 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
2200 SSL_CTX_set_tlsext_servername_arg(server_sni, state);
2203 if ( !init_dh(server_sni, state->dhparam, &dummy_errstr)
2204 || !init_ecdh(server_sni, &dummy_errstr)
2208 if ( state->server_cipher_list
2209 && !SSL_CTX_set_cipher_list(server_sni, CS state->server_cipher_list))
2212 #ifndef DISABLE_OCSP
2213 if (state->u_ocsp.server.file)
2215 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
2216 SSL_CTX_set_tlsext_status_arg(server_sni, state);
2222 if ( !expand_check(tls_verify_certificates, US"tls_verify_certificates",
2223 &expcerts, &dummy_errstr)
2224 || (rc = setup_certs(server_sni, expcerts, tls_crl, NULL,
2225 &dummy_errstr)) != OK)
2228 if (expcerts && *expcerts)
2229 setup_cert_verify(server_sni, FALSE, verify_callback_server);
2232 /* do this after setup_certs, because this can require the certs for verifying
2233 OCSP information. */
2234 if ((rc = tls_expand_session_files(server_sni, state, &dummy_errstr)) != OK)
2237 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
2238 SSL_set_SSL_CTX(s, server_sni);
2239 return SSL_TLSEXT_ERR_OK;
2241 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
2243 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
2248 #ifdef EXIM_HAVE_ALPN
2249 /*************************************************
2250 * Callback to handle ALPN *
2251 *************************************************/
2253 /* Called on server if tls_alpn nonblank after expansion,
2254 when client offers ALPN, after the SNI callback.
2255 If set and not matching the list then we dump the connection */
2258 tls_server_alpn_cb(SSL *ssl, const uschar ** out, uschar * outlen,
2259 const uschar * in, unsigned int inlen, void * arg)
2261 server_seen_alpn = TRUE;
2264 debug_printf("Received TLS ALPN offer:");
2265 for (int pos = 0, siz; pos < inlen; pos += siz+1)
2268 if (pos + 1 + siz > inlen) siz = inlen - pos - 1;
2269 debug_printf(" '%.*s'", siz, in + pos + 1);
2271 debug_printf(". Our list: '%s'\n", tls_alpn);
2274 /* Look for an acceptable ALPN */
2276 if ( inlen > 1 /* at least one name */
2277 && in[0]+1 == inlen /* filling the vector, so exactly one name */
2280 const uschar * list = tls_alpn;
2282 for (uschar * name; name = string_nextinlist(&list, &sep, NULL, 0); )
2283 if (Ustrncmp(in+1, name, in[0]) == 0)
2285 *out = in+1; /* we checked for exactly one, so can just point to it */
2287 return SSL_TLSEXT_ERR_OK; /* use ALPN */
2291 /* More than one name from clilent, or name did not match our list. */
2293 /* This will be fatal to the TLS conn; would be nice to kill TCP also.
2294 Maybe as an option in future; for now leave control to the config (must-tls). */
2296 DEBUG(D_tls) debug_printf("TLS ALPN rejected\n");
2297 return SSL_TLSEXT_ERR_ALERT_FATAL;
2299 #endif /* EXIM_HAVE_ALPN */
2303 #ifndef DISABLE_OCSP
2305 /*************************************************
2306 * Callback to handle OCSP Stapling *
2307 *************************************************/
2309 /* Called when acting as server during the TLS session setup if the client
2310 requests OCSP information with a Certificate Status Request.
2312 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
2318 tls_server_stapling_cb(SSL *s, void *arg)
2320 const exim_openssl_state_st * state = arg;
2321 ocsp_resplist * olist = state->u_ocsp.server.olist;
2322 uschar * response_der; /*XXX blob */
2323 int response_der_len;
2326 debug_printf("Received TLS status request (OCSP stapling); %s response list\n",
2327 olist ? "have" : "lack");
2329 tls_in.ocsp = OCSP_NOT_RESP;
2331 return SSL_TLSEXT_ERR_NOACK;
2333 #ifdef EXIM_HAVE_OPESSL_GET0_SERIAL
2335 const X509 * cert_sent = SSL_get_certificate(s);
2336 const ASN1_INTEGER * cert_serial = X509_get0_serialNumber(cert_sent);
2337 const BIGNUM * cert_bn = ASN1_INTEGER_to_BN(cert_serial, NULL);
2339 for (; olist; olist = olist->next)
2341 OCSP_BASICRESP * bs = OCSP_response_get1_basic(olist->resp);
2342 const OCSP_SINGLERESP * single = OCSP_resp_get0(bs, 0);
2343 const OCSP_CERTID * cid = OCSP_SINGLERESP_get0_id(single);
2344 ASN1_INTEGER * res_cert_serial;
2345 const BIGNUM * resp_bn;
2346 ASN1_OCTET_STRING * res_cert_iNameHash;
2349 (void) OCSP_id_get0_info(&res_cert_iNameHash, NULL, NULL, &res_cert_serial,
2350 (OCSP_CERTID *) cid);
2351 resp_bn = ASN1_INTEGER_to_BN(res_cert_serial, NULL);
2355 debug_printf("cert serial: %s\n", BN_bn2hex(cert_bn));
2356 debug_printf("resp serial: %s\n", BN_bn2hex(resp_bn));
2359 if (BN_cmp(cert_bn, resp_bn) == 0)
2361 DEBUG(D_tls) debug_printf("matched serial for ocsp\n");
2363 /*XXX TODO: check the rest of the list for duplicate matches.
2364 If any, need to also check the Issuer Name hash.
2365 Without this, we will provide the wrong status in the case of
2370 DEBUG(D_tls) debug_printf("not match serial for ocsp\n");
2374 DEBUG(D_tls) debug_printf("failed to find match for ocsp\n");
2375 return SSL_TLSEXT_ERR_NOACK;
2381 DEBUG(D_tls) debug_printf("OpenSSL version too early to support multi-leaf OCSP\n");
2382 return SSL_TLSEXT_ERR_NOACK;
2386 /*XXX could we do the i2d earlier, rather than during the callback? */
2387 response_der = NULL;
2388 response_der_len = i2d_OCSP_RESPONSE(olist->resp, &response_der);
2389 if (response_der_len <= 0)
2390 return SSL_TLSEXT_ERR_NOACK;
2392 SSL_set_tlsext_status_ocsp_resp(state_server.lib_state.lib_ssl,
2393 response_der, response_der_len);
2394 tls_in.ocsp = OCSP_VFIED;
2395 return SSL_TLSEXT_ERR_OK;
2400 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
2402 BIO_printf(bp, "\t%s: ", str);
2403 ASN1_GENERALIZEDTIME_print(bp, time);
2408 tls_client_stapling_cb(SSL *s, void *arg)
2410 exim_openssl_state_st * cbinfo = arg;
2411 const unsigned char * p;
2413 OCSP_RESPONSE * rsp;
2414 OCSP_BASICRESP * bs;
2417 DEBUG(D_tls) debug_printf("Received TLS status callback (OCSP stapling):\n");
2418 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
2421 /* Expect this when we requested ocsp but got none */
2422 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
2423 log_write(0, LOG_MAIN, "Required TLS certificate status not received");
2425 DEBUG(D_tls) debug_printf(" null\n");
2426 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2429 if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
2431 tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */
2432 if (LOGGING(tls_cipher))
2433 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
2435 DEBUG(D_tls) debug_printf(" parse error\n");
2439 if (!(bs = OCSP_response_get1_basic(rsp)))
2441 tls_out.ocsp = OCSP_FAILED;
2442 if (LOGGING(tls_cipher))
2443 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
2445 DEBUG(D_tls) debug_printf(" error parsing response\n");
2446 OCSP_RESPONSE_free(rsp);
2450 /* We'd check the nonce here if we'd put one in the request. */
2451 /* However that would defeat cacheability on the server so we don't. */
2453 /* This section of code reworked from OpenSSL apps source;
2454 The OpenSSL Project retains copyright:
2455 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
2459 #ifndef EXIM_HAVE_OCSP_RESP_COUNT
2460 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
2463 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
2465 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
2467 /* Use the chain that verified the server cert to verify the stapled info */
2468 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
2470 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
2471 cbinfo->u_ocsp.client.verify_store, OCSP_NOEXPLICIT)) <= 0)
2472 if (ERR_peek_error())
2474 tls_out.ocsp = OCSP_FAILED;
2475 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
2476 "Received TLS cert status response, itself unverifiable: %s",
2477 ERR_reason_error_string(ERR_peek_error()));
2478 BIO_printf(bp, "OCSP response verify failure\n");
2479 ERR_print_errors(bp);
2480 OCSP_RESPONSE_print(bp, rsp, 0);
2484 DEBUG(D_tls) debug_printf("no explicit trust for OCSP signing"
2485 " in the root CA certificate; ignoring\n");
2487 DEBUG(D_tls) debug_printf("OCSP response well-formed and signed OK\n");
2489 /*XXX So we have a good stapled OCSP status. How do we know
2490 it is for the cert of interest? OpenSSL 1.1.0 has a routine
2491 OCSP_resp_find_status() which matches on a cert id, which presumably
2492 we should use. Making an id needs OCSP_cert_id_new(), which takes
2493 issuerName, issuerKey, serialNumber. Are they all in the cert?
2495 For now, carry on blindly accepting the resp. */
2498 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
2499 OCSP_resp_count(bs) - 1;
2501 sk_OCSP_SINGLERESP_num(sresp) - 1;
2505 OCSP_SINGLERESP * single = OCSP_resp_get0(bs, idx);
2507 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
2509 /*XXX so I can see putting a loop in here to handle a rsp with >1 singleresp
2510 - but what happens with a GnuTLS-style input?
2512 we could do with a debug label for each singleresp
2513 - it has a certID with a serialNumber, but I see no API to get that
2515 status = OCSP_single_get0_status(single, &reason, &rev,
2516 &thisupd, &nextupd);
2518 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
2519 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
2520 if (!OCSP_check_validity(thisupd, nextupd,
2521 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
2523 tls_out.ocsp = OCSP_FAILED;
2524 DEBUG(D_tls) ERR_print_errors(bp);
2525 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
2529 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
2530 OCSP_cert_status_str(status));
2533 case V_OCSP_CERTSTATUS_GOOD:
2534 continue; /* the idx loop */
2535 case V_OCSP_CERTSTATUS_REVOKED:
2536 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
2537 reason != -1 ? "; reason: " : "",
2538 reason != -1 ? OCSP_crl_reason_str(reason) : "");
2539 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
2542 log_write(0, LOG_MAIN,
2543 "Server certificate status unknown, in OCSP stapling");
2551 tls_out.ocsp = OCSP_VFIED;
2555 tls_out.ocsp = OCSP_FAILED;
2556 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2561 OCSP_RESPONSE_free(rsp);
2564 #endif /*!DISABLE_OCSP*/
2567 /*************************************************
2568 * Initialize for TLS *
2569 *************************************************/
2570 /* Called from both server and client code, to do preliminary initialization
2571 of the library. We allocate and return a context structure.
2574 host connected host, if client; NULL if server
2575 ob transport options block, if client; NULL if server
2576 ocsp_file file of stapling info (server); flag for require ocsp (client)
2577 addr address if client; NULL if server (for some randomness)
2578 caller_state place to put pointer to allocated state-struct
2579 errstr error string pointer
2581 Returns: OK/DEFER/FAIL
2585 tls_init(host_item * host, smtp_transport_options_block * ob,
2586 #ifndef DISABLE_OCSP
2589 address_item *addr, exim_openssl_state_st ** caller_state,
2594 exim_openssl_state_st * state;
2597 if (host) /* client */
2599 state = store_malloc(sizeof(exim_openssl_state_st));
2600 memset(state, 0, sizeof(*state));
2601 state->certificate = ob->tls_certificate;
2602 state->privatekey = ob->tls_privatekey;
2603 state->is_server = FALSE;
2604 state->dhparam = NULL;
2605 state->lib_state = ob->tls_preload;
2609 state = &state_server;
2610 state->certificate = tls_certificate;
2611 state->privatekey = tls_privatekey;
2612 state->is_server = TRUE;
2613 state->dhparam = tls_dhparam;
2614 state->lib_state = state_server.lib_state;
2620 if (!state->lib_state.pri_string)
2621 state->server_cipher_list = NULL;
2623 #ifndef DISABLE_EVENT
2624 state->event_action = NULL;
2629 /* It turns out that we need to seed the random number generator this early in
2630 order to get the full complement of ciphers to work. It took me roughly a day
2631 of work to discover this by experiment.
2633 On systems that have /dev/urandom, SSL may automatically seed itself from
2634 there. Otherwise, we have to make something up as best we can. Double check
2637 Although we likely called this before, at daemon startup, this is a chance
2638 to mix in further variable info (time, pid) if needed. */
2640 if (!lib_rand_init(addr))
2641 return tls_error(US"RAND_status", host,
2642 US"unable to seed random number generator", errstr);
2644 /* Apply administrator-supplied work-arounds.
2645 Historically we applied just one requested option,
2646 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
2647 moved to an administrator-controlled list of options to specify and
2648 grandfathered in the first one as the default value for "openssl_options".
2650 No OpenSSL version number checks: the options we accept depend upon the
2651 availability of the option value macros from OpenSSL. */
2654 if (!tls_openssl_options_parse(openssl_options, &init_options))
2655 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
2657 /* Create a context.
2658 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
2659 negotiation in the different methods; as far as I can tell, the only
2660 *_{server,client}_method which allows negotiation is SSLv23, which exists even
2661 when OpenSSL is built without SSLv2 support.
2662 By disabling with openssl_options, we can let admins re-enable with the
2665 if (!(ctx = state->lib_state.lib_ctx))
2667 if ((rc = lib_ctx_new(&ctx, host, errstr)) != OK)
2669 state->lib_state.lib_ctx = ctx;
2672 #ifndef DISABLE_TLS_RESUME
2673 tlsp->resumption = RESUME_SUPPORTED;
2677 #ifndef DISABLE_TLS_RESUME
2678 /* Should the server offer session resumption? */
2679 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
2681 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
2682 init_options &= ~SSL_OP_NO_TICKET;
2683 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
2684 tlsp->host_resumable = TRUE;
2688 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
2689 if (!(SSL_CTX_set_options(ctx, init_options)))
2690 return tls_error(string_sprintf(
2691 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2694 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2696 /* We'd like to disable session cache unconditionally, but foolish Outlook
2697 Express clients then give up the first TLS connection and make a second one
2698 (which works). Only when there is an IMAP service on the same machine.
2699 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2700 now, until we work out a decent way of presenting control to the config. It
2701 will never be used because we use a new context every time. */
2703 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2706 /* Initialize with DH parameters if supplied */
2707 /* Initialize ECDH temp key parameter selection */
2711 if (state->lib_state.dh)
2712 { DEBUG(D_tls) debug_printf("TLS: DH params were preloaded\n"); }
2714 if (!init_dh(ctx, state->dhparam, errstr)) return DEFER;
2716 if (state->lib_state.ecdh)
2717 { DEBUG(D_tls) debug_printf("TLS: ECDH curve was preloaded\n"); }
2719 if (!init_ecdh(ctx, errstr)) return DEFER;
2722 /* Set up certificate and key (and perhaps OCSP info) */
2724 if (state->lib_state.conn_certs)
2727 debug_printf("TLS: %s certs were preloaded\n", host ? "client":"server");
2731 #ifndef DISABLE_OCSP
2734 state->u_ocsp.server.file = ocsp_file;
2735 state->u_ocsp.server.file_expanded = NULL;
2736 state->u_ocsp.server.olist = NULL;
2739 if ((rc = tls_expand_session_files(ctx, state, errstr)) != OK) return rc;
2742 /* If we need to handle SNI or OCSP, do so */
2744 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2745 # ifndef DISABLE_OCSP
2746 if (!(state->verify_stack = sk_X509_new_null()))
2748 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2753 if (!host) /* server */
2755 # ifndef DISABLE_OCSP
2756 /* We check u_ocsp.server.file, not server.olist, because we care about if
2757 the option exists, not what the current expansion might be, as SNI might
2758 change the certificate and OCSP file in use between now and the time the
2759 callback is invoked. */
2760 if (state->u_ocsp.server.file)
2762 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2763 SSL_CTX_set_tlsext_status_arg(ctx, state);
2766 /* We always do this, so that $tls_sni is available even if not used in
2768 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2769 SSL_CTX_set_tlsext_servername_arg(ctx, state);
2771 # ifdef EXIM_HAVE_ALPN
2772 if (tls_alpn && *tls_alpn)
2775 if ( expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr)
2776 && *exp_alpn && !isblank(*exp_alpn))
2778 tls_alpn = exp_alpn; /* subprocess so ok to overwrite */
2779 SSL_CTX_set_alpn_select_cb(ctx, tls_server_alpn_cb, state);
2786 # ifndef DISABLE_OCSP
2788 if(ocsp_file) /* wanting stapling */
2790 if (!(state->u_ocsp.client.verify_store = X509_STORE_new()))
2792 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2795 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2796 SSL_CTX_set_tlsext_status_arg(ctx, state);
2801 state->verify_cert_hostnames = NULL;
2803 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2804 /* Set up the RSA callback */
2805 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2808 /* Finally, set the session cache timeout, and we are done.
2809 The period appears to be also used for (server-generated) session tickets */
2811 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2812 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2814 *caller_state = state;
2822 /*************************************************
2823 * Get name of cipher in use *
2824 *************************************************/
2827 Argument: pointer to an SSL structure for the connection
2828 pointer to number of bits for cipher
2829 Returns: pointer to allocated string in perm-pool
2833 construct_cipher_name(SSL * ssl, const uschar * ver, int * bits)
2835 int pool = store_pool;
2836 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2837 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2838 the accessor functions use const in the prototype. */
2840 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2843 SSL_CIPHER_get_bits(c, bits);
2845 store_pool = POOL_PERM;
2846 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2848 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2853 /* Get IETF-standard name for ciphersuite.
2854 Argument: pointer to an SSL structure for the connection
2855 Returns: pointer to string
2858 static const uschar *
2859 cipher_stdname_ssl(SSL * ssl)
2861 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2862 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2864 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2865 return cipher_stdname(id >> 8, id & 0xff);
2870 static const uschar *
2871 tlsver_name(SSL * ssl)
2874 int pool = store_pool;
2876 store_pool = POOL_PERM;
2877 s = string_copy(US SSL_get_version(ssl));
2879 if ((p = Ustrchr(s, 'v'))) /* TLSv1.2 -> TLS1.2 */
2880 for (;; p++) if (!(*p = p[1])) break;
2886 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2888 /*XXX we might consider a list-of-certs variable for the cert chain.
2889 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2890 in list-handling functions, also consider the difference between the entire
2891 chain and the elements sent by the peer. */
2893 tlsp->peerdn = NULL;
2895 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2896 if (!tlsp->peercert)
2897 tlsp->peercert = SSL_get_peer_certificate(ssl);
2898 /* Beware anonymous ciphers which lead to server_cert being NULL */
2900 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2901 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2904 int oldpool = store_pool;
2906 peerdn[siz-1] = '\0'; /* paranoia */
2907 store_pool = POOL_PERM;
2908 tlsp->peerdn = string_copy(peerdn);
2909 store_pool = oldpool;
2911 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2912 but they don't get called on session-resumption. So use the official
2913 interface, which uses the resumed value. Unfortunately this claims verified
2914 when it actually failed but we're in try-verify mode, due to us wanting the
2915 knowlege that it failed so needing to have the callback and forcing a
2916 permissive return. If we don't force it, the TLS startup is failed.
2917 The extra bit of information is set in verify_override in the cb, stashed
2918 for resumption next to the TLS session, and used here. */
2920 if (!tlsp->verify_override)
2921 tlsp->certificate_verified =
2923 tlsp->dane_verified ||
2925 SSL_get_verify_result(ssl) == X509_V_OK;
2933 /*************************************************
2934 * Set up for verifying certificates *
2935 *************************************************/
2937 #ifndef DISABLE_OCSP
2938 /* Load certs from file, return TRUE on success */
2941 chain_from_pem_file(const uschar * file, STACK_OF(X509) ** vp)
2944 STACK_OF(X509) * verify_stack = *vp;
2947 while (sk_X509_num(verify_stack) > 0)
2948 X509_free(sk_X509_pop(verify_stack));
2950 verify_stack = sk_X509_new_null();
2952 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
2953 for (X509 * x; x = PEM_read_bio_X509(bp, NULL, 0, NULL); )
2954 sk_X509_push(verify_stack, x);
2963 /* Called by both client and server startup; on the server possibly
2964 repeated after a Server Name Indication.
2967 sctx SSL_CTX* to initialise
2968 certs certs file, expanded
2969 crl CRL file or NULL
2970 host NULL in a server; the remote host in a client
2971 errstr error string pointer
2973 Returns: OK/DEFER/FAIL
2977 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
2980 uschar *expcerts, *expcrl;
2982 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
2984 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
2986 if (expcerts && *expcerts)
2988 /* Tell the library to use its compiled-in location for the system default
2989 CA bundle. Then add the ones specified in the config, if any. */
2991 if (!SSL_CTX_set_default_verify_paths(sctx))
2992 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
2994 if (Ustrcmp(expcerts, "system") != 0 && Ustrncmp(expcerts, "system,", 7) != 0)
2996 struct stat statbuf;
2998 if (Ustat(expcerts, &statbuf) < 0)
3000 log_write(0, LOG_MAIN|LOG_PANIC,
3001 "failed to stat %s for certificates", expcerts);
3007 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
3008 { file = NULL; dir = expcerts; }
3011 STACK_OF(X509) * verify_stack =
3012 #ifndef DISABLE_OCSP
3013 !host ? state_server.verify_stack :
3016 STACK_OF(X509) ** vp = &verify_stack;
3018 file = expcerts; dir = NULL;
3019 #ifndef DISABLE_OCSP
3020 /* In the server if we will be offering an OCSP proof, load chain from
3021 file for verifying the OCSP proof at load time. */
3023 /*XXX Glitch! The file here is tls_verify_certs: the chain for verifying the client cert.
3024 This is inconsistent with the need to verify the OCSP proof of the server cert.
3027 && statbuf.st_size > 0
3028 && state_server.u_ocsp.server.file
3029 && !chain_from_pem_file(file, vp)
3032 log_write(0, LOG_MAIN|LOG_PANIC,
3033 "failed to load cert chain from %s", file);
3039 /* If a certificate file is empty, the load function fails with an
3040 unhelpful error message. If we skip it, we get the correct behaviour (no
3041 certificates are recognized, but the error message is still misleading (it
3042 says no certificate was supplied). But this is better. */
3044 if ( (!file || statbuf.st_size > 0)
3045 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
3046 return tls_error(US"SSL_CTX_load_verify_locations",
3047 host, NULL, errstr);
3049 /* On the server load the list of CAs for which we will accept certs, for
3050 sending to the client. This is only for the one-file
3051 tls_verify_certificates variant.
3052 If a list isn't loaded into the server, but some verify locations are set,
3053 the server end appears to make a wildcard request for client certs.
3054 Meanwhile, the client library as default behaviour *ignores* the list
3055 we send over the wire - see man SSL_CTX_set_client_cert_cb.
3056 Because of this, and that the dir variant is likely only used for
3057 the public-CA bundle (not for a private CA), not worth fixing. */
3061 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
3062 int i = sk_X509_NAME_num(names);
3064 if (!host) SSL_CTX_set_client_CA_list(sctx, names);
3065 DEBUG(D_tls) debug_printf("Added %d additional certificate authorit%s\n",
3066 i, i>1 ? "ies":"y");
3070 debug_printf("Added dir for additional certificate authorities\n");
3074 /* Handle a certificate revocation list. */
3076 #if OPENSSL_VERSION_NUMBER > 0x00907000L
3078 /* This bit of code is now the version supplied by Lars Mainka. (I have
3079 merely reformatted it into the Exim code style.)
3081 "From here I changed the code to add support for multiple crl's
3082 in pem format in one file or to support hashed directory entries in
3083 pem format instead of a file. This method now uses the library function
3084 X509_STORE_load_locations to add the CRL location to the SSL context.
3085 OpenSSL will then handle the verify against CA certs and CRLs by
3086 itself in the verify callback." */
3088 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
3089 if (expcrl && *expcrl)
3091 struct stat statbufcrl;
3092 if (Ustat(expcrl, &statbufcrl) < 0)
3094 log_write(0, LOG_MAIN|LOG_PANIC,
3095 "failed to stat %s for certificates revocation lists", expcrl);
3100 /* is it a file or directory? */
3102 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
3103 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
3107 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
3113 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
3115 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
3116 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
3118 /* setting the flags to check against the complete crl chain */
3120 X509_STORE_set_flags(cvstore,
3121 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
3125 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
3133 /*************************************************
3134 * Start a TLS session in a server *
3135 *************************************************/
3136 /* This is called when Exim is running as a server, after having received
3137 the STARTTLS command. It must respond to that command, and then negotiate
3141 errstr pointer to error message
3143 Returns: OK on success
3144 DEFER for errors before the start of the negotiation
3145 FAIL for errors during the negotiation; the server can't
3150 tls_server_start(uschar ** errstr)
3153 uschar * expciphers;
3154 exim_openssl_state_st * dummy_statep;
3157 static uschar peerdn[256];
3159 /* Check for previous activation */
3161 if (tls_in.active.sock >= 0)
3163 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
3164 smtp_printf("554 Already in TLS\r\n", FALSE);
3168 /* Initialize the SSL library. If it fails, it will already have logged
3171 rc = tls_init(NULL, NULL,
3172 #ifndef DISABLE_OCSP
3175 NULL, &dummy_statep, &tls_in, errstr);
3176 if (rc != OK) return rc;
3177 ctx = state_server.lib_state.lib_ctx;
3179 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3180 were historically separated by underscores. So that I can use either form in my
3181 tests, and also for general convenience, we turn underscores into hyphens here.
3183 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
3184 for TLS 1.3 . Since we do not call it at present we get the default list:
3185 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
3188 if (state_server.lib_state.pri_string)
3189 { DEBUG(D_tls) debug_printf("TLS: cipher list was preloaded\n"); }
3192 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
3197 normalise_ciphers(&expciphers, tls_require_ciphers);
3198 if ((rc = server_load_ciphers(ctx, &state_server, expciphers, errstr)) != OK)
3203 /* If this is a host for which certificate verification is mandatory or
3204 optional, set up appropriately. */
3206 tls_in.certificate_verified = FALSE;
3208 tls_in.dane_verified = FALSE;
3210 server_verify_callback_called = FALSE;
3212 if (verify_check_host(&tls_verify_hosts) == OK)
3213 server_verify_optional = FALSE;
3214 else if (verify_check_host(&tls_try_verify_hosts) == OK)
3215 server_verify_optional = TRUE;
3221 if (!expand_check(tls_verify_certificates, US"tls_verify_certificates",
3224 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3226 if (state_server.lib_state.cabundle)
3227 { DEBUG(D_tls) debug_printf("TLS: CA bundle for server was preloaded\n"); }
3229 if ((rc = setup_certs(ctx, expcerts, tls_crl, NULL, errstr)) != OK)
3232 if (expcerts && *expcerts)
3233 setup_cert_verify(ctx, server_verify_optional, verify_callback_server);
3237 #ifndef DISABLE_TLS_RESUME
3238 # if OPENSSL_VERSION_NUMBER < 0x30000000L
3239 SSL_CTX_set_tlsext_ticket_key_cb(ctx, ticket_key_callback);
3240 /* despite working, appears to always return failure, so ignoring */
3242 SSL_CTX_set_tlsext_ticket_key_evp_cb(ctx, ticket_key_callback);
3243 /* despite working, appears to always return failure, so ignoring */
3247 #ifdef OPENSSL_HAVE_NUM_TICKETS
3248 # ifndef DISABLE_TLS_RESUME
3249 SSL_CTX_set_num_tickets(ctx, tls_in.host_resumable ? 1 : 0);
3251 SSL_CTX_set_num_tickets(ctx, 0); /* send no TLS1.3 stateful-tickets */
3256 /* Prepare for new connection */
3258 if (!(ssl = SSL_new(ctx)))
3259 return tls_error(US"SSL_new", NULL, NULL, errstr);
3260 state_server.lib_state.lib_ssl = ssl;
3262 /* Warning: we used to SSL_clear(ssl) here, it was removed.
3264 * With the SSL_clear(), we get strange interoperability bugs with
3265 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
3266 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
3268 * The SSL_clear() call is to let an existing SSL* be reused, typically after
3269 * session shutdown. In this case, we have a brand new object and there's no
3270 * obvious reason to immediately clear it. I'm guessing that this was
3271 * originally added because of incomplete initialisation which the clear fixed,
3272 * in some historic release.
3275 /* Set context and tell client to go ahead, except in the case of TLS startup
3276 on connection, where outputting anything now upsets the clients and tends to
3277 make them disconnect. We need to have an explicit fflush() here, to force out
3278 the response. Other smtp_printf() calls do not need it, because in non-TLS
3279 mode, the fflush() happens when smtp_getc() is called. */
3281 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
3282 if (!tls_in.on_connect)
3284 smtp_printf("220 TLS go ahead\r\n", FALSE);
3288 /* Now negotiate the TLS session. We put our own timer on it, since it seems
3289 that the OpenSSL library doesn't. */
3291 SSL_set_wfd(ssl, fileno(smtp_out));
3292 SSL_set_rfd(ssl, fileno(smtp_in));
3293 SSL_set_accept_state(ssl);
3295 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
3298 sigalrm_seen = FALSE;
3299 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3300 rc = SSL_accept(ssl);
3305 int error = SSL_get_error(ssl, rc);
3308 case SSL_ERROR_NONE:
3311 case SSL_ERROR_ZERO_RETURN:
3312 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3313 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
3315 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
3318 tls_close(NULL, TLS_NO_SHUTDOWN);
3321 /* Handle genuine errors */
3325 int r = ERR_GET_REASON(ERR_peek_error());
3326 if ( r == SSL_R_WRONG_VERSION_NUMBER
3327 #ifdef SSL_R_VERSION_TOO_LOW
3328 || r == SSL_R_VERSION_TOO_LOW
3330 || r == SSL_R_UNKNOWN_PROTOCOL || r == SSL_R_UNSUPPORTED_PROTOCOL)
3331 s = string_sprintf("%s (%s)", s, SSL_get_version(ssl));
3332 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : s, errstr);
3337 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3338 if (error == SSL_ERROR_SYSCALL)
3342 *errstr = US"SSL_accept: TCP connection closed by peer";
3345 DEBUG(D_tls) debug_printf(" - syscall %s\n", strerror(errno));
3347 (void) tls_error(US"SSL_accept", NULL,
3348 sigalrm_seen ? US"timed out"
3349 : ERR_peek_error() ? NULL : string_sprintf("ret %d", error),
3355 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
3356 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
3357 anon-authentication ciphersuite negotiated. */
3359 #ifndef DISABLE_TLS_RESUME
3360 if (SSL_session_reused(ssl))
3362 tls_in.resumption |= RESUME_USED;
3363 DEBUG(D_tls) debug_printf("Session reused\n");
3367 #ifdef EXIM_HAVE_ALPN
3368 /* If require-alpn, check server_seen_alpn here. Else abort TLS */
3369 if (!tls_alpn || !*tls_alpn)
3370 { DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n"); }
3371 else if (!server_seen_alpn)
3372 if (verify_check_host(&hosts_require_alpn) == OK)
3374 /* We'd like to send a definitive Alert but OpenSSL provides no facility */
3376 tls_error(US"handshake", NULL, US"ALPN required but not negotiated", errstr);
3380 { DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n"); }
3383 const uschar * name;
3385 SSL_get0_alpn_selected(ssl, &name, &len);
3387 debug_printf("ALPN negotiated: '%.*s'\n", (int)*name, name+1);
3389 debug_printf("ALPN: no protocol negotiated\n");
3394 /* TLS has been set up. Record data for the connection,
3395 adjust the input functions to read via TLS, and initialize things. */
3397 #ifdef SSL_get_extms_support
3398 tls_in.ext_master_secret = SSL_get_extms_support(ssl) == 1;
3400 peer_cert(ssl, &tls_in, peerdn, sizeof(peerdn));
3402 tls_in.ver = tlsver_name(ssl);
3403 tls_in.cipher = construct_cipher_name(ssl, tls_in.ver, &tls_in.bits);
3404 tls_in.cipher_stdname = cipher_stdname_ssl(ssl);
3409 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)))
3410 debug_printf("Shared ciphers: %s\n", buf);
3412 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3414 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3415 SSL_SESSION_print_keylog(bp, SSL_get_session(ssl));
3420 #ifdef EXIM_HAVE_SESSION_TICKET
3422 SSL_SESSION * ss = SSL_get_session(ssl);
3423 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
3424 debug_printf("The session has a ticket, life %lu seconds\n",
3425 SSL_SESSION_get_ticket_lifetime_hint(ss));
3430 /* Record the certificate we presented */
3432 X509 * crt = SSL_get_certificate(ssl);
3433 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
3436 /* Channel-binding info for authenticators
3437 See description in https://paquier.xyz/postgresql-2/channel-binding-openssl/ */
3440 size_t len = SSL_get_peer_finished(ssl, &c, 0);
3441 int old_pool = store_pool;
3443 SSL_get_peer_finished(ssl, s = store_get((int)len, FALSE), len);
3444 store_pool = POOL_PERM;
3445 tls_in.channelbinding = b64encode_taint(CUS s, (int)len, FALSE);
3446 store_pool = old_pool;
3447 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p\n", tls_in.channelbinding);
3450 /* Only used by the server-side tls (tls_in), including tls_getc.
3451 Client-side (tls_out) reads (seem to?) go via
3452 smtp_read_response()/ip_recv().
3453 Hence no need to duplicate for _in and _out.
3455 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
3456 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
3457 ssl_xfer_eof = ssl_xfer_error = FALSE;
3459 receive_getc = tls_getc;
3460 receive_getbuf = tls_getbuf;
3461 receive_get_cache = tls_get_cache;
3462 receive_hasc = tls_hasc;
3463 receive_ungetc = tls_ungetc;
3464 receive_feof = tls_feof;
3465 receive_ferror = tls_ferror;
3467 tls_in.active.sock = fileno(smtp_out);
3468 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
3476 tls_client_basic_ctx_init(SSL_CTX * ctx,
3477 host_item * host, smtp_transport_options_block * ob, exim_openssl_state_st * state,
3482 /* Back-compatible old behaviour if tls_verify_certificates is set but both
3483 tls_verify_hosts and tls_try_verify_hosts are not set. Check only the specified
3484 host patterns if one of them is set with content. */
3486 if ( ( ( !ob->tls_verify_hosts || !ob->tls_verify_hosts
3487 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3489 && ( !ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts
3490 || Ustrcmp(ob->tls_try_verify_hosts, ":") == 0
3493 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
3495 client_verify_optional = FALSE;
3496 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
3497 client_verify_optional = TRUE;
3503 if (!expand_check(ob->tls_verify_certificates, US"tls_verify_certificates",
3506 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
3508 if (state->lib_state.cabundle)
3509 { DEBUG(D_tls) debug_printf("TLS: CA bundle was preloaded\n"); }
3511 if ((rc = setup_certs(ctx, expcerts, ob->tls_crl, host, errstr)) != OK)
3514 if (expcerts && *expcerts)
3515 setup_cert_verify(ctx, client_verify_optional, verify_callback_client);
3518 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
3520 state->verify_cert_hostnames =
3522 string_domain_utf8_to_alabel(host->certname, NULL);
3526 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
3527 state->verify_cert_hostnames);
3535 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
3538 const char * hostnames[2] = { CS host->name, NULL };
3541 if (DANESSL_init(ssl, NULL, hostnames) != 1)
3542 return tls_error(US"hostnames load", host, NULL, errstr);
3544 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
3545 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
3546 ) if (rr->type == T_TLSA && rr->size > 3)
3548 const uschar * p = rr->data;
3549 uint8_t usage, selector, mtype;
3550 const char * mdname;
3554 /* Only DANE-TA(2) and DANE-EE(3) are supported */
3555 if (usage != 2 && usage != 3) continue;
3562 default: continue; /* Only match-types 0, 1, 2 are supported */
3563 case 0: mdname = NULL; break;
3564 case 1: mdname = "sha256"; break;
3565 case 2: mdname = "sha512"; break;
3569 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
3572 return tls_error(US"tlsa load", host, NULL, errstr);
3573 case 0: /* action not taken */
3577 tls_out.tlsa_usage |= 1<<usage;
3583 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
3586 #endif /*SUPPORT_DANE*/
3590 #ifndef DISABLE_TLS_RESUME
3591 /* On the client, get any stashed session for the given IP from hints db
3592 and apply it to the ssl-connection for attempted resumption. */
3595 tls_retrieve_session(tls_support * tlsp, SSL * ssl, const uschar * key)
3597 tlsp->resumption |= RESUME_SUPPORTED;
3598 if (tlsp->host_resumable)
3600 dbdata_tls_session * dt;
3602 open_db dbblock, * dbm_file;
3604 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
3605 DEBUG(D_tls) debug_printf("checking for resumable session for %s\n", key);
3606 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3608 /* key for the db is the IP */
3609 if ((dt = dbfn_read_with_length(dbm_file, key, &len)))
3611 SSL_SESSION * ss = NULL;
3612 const uschar * sess_asn1 = dt->session;
3614 len -= sizeof(dbdata_tls_session);
3615 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
3619 ERR_error_string_n(ERR_get_error(),
3620 ssl_errstring, sizeof(ssl_errstring));
3621 debug_printf("decoding session: %s\n", ssl_errstring);
3626 unsigned long lifetime =
3627 #ifdef EXIM_HAVE_SESSION_TICKET
3628 SSL_SESSION_get_ticket_lifetime_hint(ss);
3629 #else /* Use, fairly arbitrilarily, what we as server would */
3630 f.running_in_test_harness ? 6 : ssl_session_timeout;
3632 if (lifetime + dt->time_stamp < time(NULL))
3634 DEBUG(D_tls) debug_printf("session expired\n");
3635 dbfn_delete(dbm_file, key);
3637 else if (!SSL_set_session(ssl, ss))
3641 ERR_error_string_n(ERR_get_error(),
3642 ssl_errstring, sizeof(ssl_errstring));
3643 debug_printf("applying session to ssl: %s\n", ssl_errstring);
3648 DEBUG(D_tls) debug_printf("good session\n");
3649 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
3650 tlsp->verify_override = dt->verify_override;
3651 tlsp->ocsp = dt->ocsp;
3656 DEBUG(D_tls) debug_printf("no session record\n");
3657 dbfn_close(dbm_file);
3663 /* On the client, save the session for later resumption */
3666 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
3668 exim_openssl_state_st * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
3671 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
3673 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
3675 # ifdef OPENSSL_HAVE_NUM_TICKETS
3676 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
3679 int len = i2d_SSL_SESSION(ss, NULL);
3680 int dlen = sizeof(dbdata_tls_session) + len;
3681 dbdata_tls_session * dt = store_get(dlen, TRUE);
3682 uschar * s = dt->session;
3683 open_db dbblock, * dbm_file;
3685 DEBUG(D_tls) debug_printf("session is resumable\n");
3686 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
3688 dt->verify_override = tlsp->verify_override;
3689 dt->ocsp = tlsp->ocsp;
3690 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
3692 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3694 const uschar * key = cbinfo->host->address;
3695 dbfn_delete(dbm_file, key);
3696 dbfn_write(dbm_file, key, dt, dlen);
3697 dbfn_close(dbm_file);
3698 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
3707 tls_client_ctx_resume_prehandshake(
3708 exim_openssl_client_tls_ctx * exim_client_ctx, tls_support * tlsp,
3709 smtp_transport_options_block * ob, host_item * host)
3711 /* Should the client request a session resumption ticket? */
3712 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
3714 tlsp->host_resumable = TRUE;
3716 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
3717 SSL_SESS_CACHE_CLIENT
3718 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
3719 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
3724 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
3725 host_item * host, uschar ** errstr)
3727 if (tlsp->host_resumable)
3730 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
3731 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
3733 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
3734 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_state))
3736 tls_error(US"set ex_data", host, NULL, errstr);
3739 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_state);
3742 tlsp->resumption = RESUME_SUPPORTED;
3743 /* Pick up a previous session, saved on an old ticket */
3744 tls_retrieve_session(tlsp, ssl, host->address);
3749 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
3752 if (SSL_session_reused(exim_client_ctx->ssl))
3754 DEBUG(D_tls) debug_printf("The session was reused\n");
3755 tlsp->resumption |= RESUME_USED;
3758 #endif /* !DISABLE_TLS_RESUME */
3761 #ifdef EXIM_HAVE_ALPN
3762 /* Expand and convert an Exim list to an ALPN list. False return for fail.
3763 NULL plist return for silent no-ALPN.
3767 tls_alpn_plist(const uschar * tls_alpn, const uschar ** plist, unsigned * plen,
3772 if (!expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr))
3777 DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
3782 /* The server implementation only accepts exactly one protocol name
3783 but it's little extra code complexity in the client. */
3785 const uschar * list = exp_alpn;
3786 uschar * p = store_get(Ustrlen(exp_alpn), is_tainted(exp_alpn)), * s, * t;
3790 for (t = p; s = string_nextinlist(&list, &sep, NULL, 0); t += len)
3792 *t++ = len = (uschar) Ustrlen(s);
3795 *plist = (*plen = t - p) ? p : NULL;
3799 #endif /* EXIM_HAVE_ALPN */
3802 /*************************************************
3803 * Start a TLS session in a client *
3804 *************************************************/
3806 /* Called from the smtp transport after STARTTLS has been accepted.
3809 cctx connection context
3810 conn_args connection details
3811 cookie datum for randomness; can be NULL
3812 tlsp record details of TLS channel configuration here; must be non-NULL
3813 errstr error string pointer
3815 Returns: TRUE for success with TLS session context set in connection context,
3820 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3821 void * cookie, tls_support * tlsp, uschar ** errstr)
3823 host_item * host = conn_args->host; /* for msgs and option-tests */
3824 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3825 smtp_transport_options_block * ob = tb
3826 ? (smtp_transport_options_block *)tb->options_block
3827 : &smtp_transport_option_defaults;
3828 exim_openssl_client_tls_ctx * exim_client_ctx;
3829 uschar * expciphers;
3831 static uschar peerdn[256];
3833 #ifndef DISABLE_OCSP
3834 BOOL request_ocsp = FALSE;
3835 BOOL require_ocsp = FALSE;
3839 store_pool = POOL_PERM;
3840 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), FALSE);
3841 exim_client_ctx->corked = NULL;
3845 tlsp->tlsa_usage = 0;
3848 #ifndef DISABLE_OCSP
3850 # ifdef SUPPORT_DANE
3851 /*XXX this should be moved to caller, to be common across gnutls/openssl */
3852 if ( conn_args->dane
3853 && ob->hosts_request_ocsp[0] == '*'
3854 && ob->hosts_request_ocsp[1] == '\0'
3857 /* Unchanged from default. Use a safer one under DANE */
3858 request_ocsp = TRUE;
3859 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
3860 " {= {4}{$tls_out_tlsa_usage}} } "
3866 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
3867 request_ocsp = TRUE;
3869 # ifdef SUPPORT_DANE
3873 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3877 rc = tls_init(host, ob,
3878 #ifndef DISABLE_OCSP
3879 (void *)(long)request_ocsp,
3881 cookie, &client_static_state, tlsp, errstr);
3882 if (rc != OK) return FALSE;
3884 exim_client_ctx->ctx = client_static_state->lib_state.lib_ctx;
3886 tlsp->certificate_verified = FALSE;
3887 client_verify_callback_called = FALSE;
3891 if (conn_args->dane)
3893 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
3894 other failures should be treated as problems. */
3895 if (ob->dane_require_tls_ciphers &&
3896 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3897 &expciphers, errstr))
3899 if (expciphers && *expciphers == '\0')
3902 normalise_ciphers(&expciphers, ob->dane_require_tls_ciphers);
3907 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
3908 &expciphers, errstr))
3911 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3912 are separated by underscores. So that I can use either form in my tests, and
3913 also for general convenience, we turn underscores into hyphens here. */
3915 normalise_ciphers(&expciphers, ob->tls_require_ciphers);
3920 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
3921 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
3923 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
3929 if (conn_args->dane)
3931 SSL_CTX_set_verify(exim_client_ctx->ctx,
3932 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
3933 verify_callback_client_dane);
3935 if (!DANESSL_library_init())
3937 tls_error(US"library init", host, NULL, errstr);
3940 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
3942 tls_error(US"context init", host, NULL, errstr);
3950 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
3951 client_static_state, errstr) != OK)
3954 #ifndef DISABLE_TLS_RESUME
3955 tls_client_ctx_resume_prehandshake(exim_client_ctx, tlsp, ob, host);
3959 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
3961 tls_error(US"SSL_new", host, NULL, errstr);
3964 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
3966 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
3967 SSL_set_connect_state(exim_client_ctx->ssl);
3971 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
3975 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
3977 else if (!Ustrlen(tlsp->sni))
3981 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
3982 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
3983 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
3985 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
3992 #ifdef EXIM_HAVE_ALPN
3994 const uschar * plist;
3997 if (!tls_alpn_plist(ob->tls_alpn, &plist, &plen, errstr))
4000 if (SSL_set_alpn_protos(exim_client_ctx->ssl, plist, plen) != 0)
4002 tls_error(US"alpn init", host, NULL, errstr);
4006 DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
4009 log_write(0, LOG_MAIN, "ALPN unusable with this OpenSSL library version; ignoring \"%s\"\n",
4014 if (conn_args->dane)
4015 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
4019 #ifndef DISABLE_OCSP
4020 /* Request certificate status at connection-time. If the server
4021 does OCSP stapling we will get the callback (set in tls_init()) */
4022 # ifdef SUPPORT_DANE
4026 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
4027 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
4029 { /* Re-eval now $tls_out_tlsa_usage is populated. If
4030 this means we avoid the OCSP request, we wasted the setup
4031 cost in tls_init(). */
4032 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
4033 request_ocsp = require_ocsp
4034 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
4041 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
4042 client_static_state->u_ocsp.client.verify_required = require_ocsp;
4043 tlsp->ocsp = OCSP_NOT_RESP;
4047 #ifndef DISABLE_TLS_RESUME
4048 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
4053 #ifndef DISABLE_EVENT
4054 client_static_state->event_action = tb ? tb->event_action : NULL;
4057 /* There doesn't seem to be a built-in timeout on connection. */
4059 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
4060 sigalrm_seen = FALSE;
4061 ALARM(ob->command_timeout);
4062 rc = SSL_connect(exim_client_ctx->ssl);
4066 if (conn_args->dane)
4067 DANESSL_cleanup(exim_client_ctx->ssl);
4072 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
4078 debug_printf("SSL_connect succeeded\n");
4079 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
4081 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
4082 SSL_SESSION_print_keylog(bp, SSL_get_session(exim_client_ctx->ssl));
4088 #ifndef DISABLE_TLS_RESUME
4089 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
4092 #ifdef EXIM_HAVE_ALPN
4093 if (ob->tls_alpn) /* We requested. See what was negotiated. */
4095 const uschar * name;
4098 SSL_get0_alpn_selected(exim_client_ctx->ssl, &name, &len);
4100 { DEBUG(D_tls) debug_printf("ALPN negotiated %u: '%.*s'\n", len, (int)*name, name+1); }
4101 else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
4103 /* Would like to send a relevant fatal Alert, but OpenSSL has no API */
4104 tls_error(US"handshake", host, US"ALPN required but not negotiated", errstr);
4110 #ifdef SSL_get_extms_support
4111 tlsp->ext_master_secret = SSL_get_extms_support(exim_client_ctx->ssl) == 1;
4113 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
4115 tlsp->ver = tlsver_name(exim_client_ctx->ssl);
4116 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, tlsp->ver, &tlsp->bits);
4117 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
4119 /* Record the certificate we presented */
4121 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
4122 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
4125 /*XXX will this work with continued-TLS? */
4126 /* Channel-binding info for authenticators */
4129 size_t len = SSL_get_finished(exim_client_ctx->ssl, &c, 0);
4130 int old_pool = store_pool;
4132 SSL_get_finished(exim_client_ctx->ssl, s = store_get((int)len, TRUE), len);
4133 store_pool = POOL_PERM;
4134 tlsp->channelbinding = b64encode_taint(CUS s, (int)len, TRUE);
4135 store_pool = old_pool;
4136 DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage %p %p\n", tlsp->channelbinding, tlsp);
4139 tlsp->active.sock = cctx->sock;
4140 tlsp->active.tls_ctx = exim_client_ctx;
4141 cctx->tls_ctx = exim_client_ctx;
4150 tls_refill(unsigned lim)
4152 SSL * ssl = state_server.lib_state.lib_ssl;
4156 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4157 ssl_xfer_buffer, ssl_xfer_buffer_size);
4160 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
4161 inbytes = SSL_read(ssl, CS ssl_xfer_buffer,
4162 MIN(ssl_xfer_buffer_size, lim));
4163 error = SSL_get_error(ssl, inbytes);
4164 if (smtp_receive_timeout > 0) ALARM_CLR(0);
4166 if (had_command_timeout) /* set by signal handler */
4167 smtp_command_timeout_exit(); /* does not return */
4168 if (had_command_sigterm)
4169 smtp_command_sigterm_exit();
4170 if (had_data_timeout)
4171 smtp_data_timeout_exit();
4172 if (had_data_sigint)
4173 smtp_data_sigint_exit();
4175 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
4176 closed down, not that the socket itself has been closed down. Revert to
4177 non-SSL handling. */
4181 case SSL_ERROR_NONE:
4184 case SSL_ERROR_ZERO_RETURN:
4185 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4187 if (SSL_get_shutdown(ssl) == SSL_RECEIVED_SHUTDOWN)
4190 tls_close(NULL, TLS_NO_SHUTDOWN);
4193 /* Handle genuine errors */
4195 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4196 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
4197 ssl_xfer_error = TRUE;
4201 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
4202 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
4203 debug_printf(" - syscall %s\n", strerror(errno));
4204 ssl_xfer_error = TRUE;
4208 #ifndef DISABLE_DKIM
4209 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
4211 ssl_xfer_buffer_hwm = inbytes;
4212 ssl_xfer_buffer_lwm = 0;
4217 /*************************************************
4218 * TLS version of getc *
4219 *************************************************/
4221 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
4222 it refills the buffer via the SSL reading function.
4224 Arguments: lim Maximum amount to read/buffer
4225 Returns: the next character or EOF
4227 Only used by the server-side TLS.
4231 tls_getc(unsigned lim)
4233 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4234 if (!tls_refill(lim))
4235 return ssl_xfer_error ? EOF : smtp_getc(lim);
4237 /* Something in the buffer; return next uschar */
4239 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
4245 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm;
4249 tls_getbuf(unsigned * len)
4254 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
4255 if (!tls_refill(*len))
4257 if (!ssl_xfer_error) return smtp_getbuf(len);
4262 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
4264 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
4265 ssl_xfer_buffer_lwm += size;
4272 tls_get_cache(unsigned lim)
4274 #ifndef DISABLE_DKIM
4275 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
4276 debug_printf("tls_get_cache\n");
4280 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
4286 tls_could_getc(void)
4288 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm
4289 || SSL_pending(state_server.lib_state.lib_ssl) > 0;
4293 /*************************************************
4294 * Read bytes from TLS channel *
4295 *************************************************/
4299 ct_ctx client context pointer, or NULL for the one global server context
4303 Returns: the number of bytes read
4304 -1 after a failed read, including EOF
4306 Only used by the client-side TLS.
4310 tls_read(void * ct_ctx, uschar *buff, size_t len)
4312 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4313 : state_server.lib_state.lib_ssl;
4317 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
4318 buff, (unsigned int)len);
4321 inbytes = SSL_read(ssl, CS buff, len);
4322 error = SSL_get_error(ssl, inbytes);
4324 if (error == SSL_ERROR_ZERO_RETURN)
4326 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
4329 else if (error != SSL_ERROR_NONE)
4339 /*************************************************
4340 * Write bytes down TLS channel *
4341 *************************************************/
4345 ct_ctx client context pointer, or NULL for the one global server context
4348 more further data expected soon
4350 Returns: the number of bytes after a successful write,
4351 -1 after a failed write
4353 Used by both server-side and client-side TLS. Calling with len zero and more unset
4354 will flush buffered writes; buff can be null for this case.
4358 tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
4361 int outbytes, error;
4363 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl
4364 : state_server.lib_state.lib_ssl;
4365 static gstring * server_corked = NULL;
4366 gstring ** corkedp = ct_ctx
4367 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
4368 gstring * corked = *corkedp;
4370 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
4371 buff, (unsigned long)len, more ? ", more" : "");
4373 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
4374 "more" is notified. This hack is only ok if small amounts are involved AND only
4375 one stream does it, in one context (i.e. no store reset). Currently it is used
4376 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
4377 We support callouts done by the server process by using a separate client
4378 context for the stashed information. */
4379 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
4380 a store reset there, so use POOL_PERM. */
4381 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
4385 if (!len) buff = US &error; /* dummy just so that string_catn is ok */
4387 int save_pool = store_pool;
4388 store_pool = POOL_PERM;
4390 corked = string_catn(corked, buff, len);
4392 store_pool = save_pool;
4399 buff = CUS corked->s;
4404 for (int left = len; left > 0;)
4406 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
4408 outbytes = SSL_write(ssl, CS buff, left);
4409 error = SSL_get_error(ssl, outbytes);
4410 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
4413 case SSL_ERROR_NONE: /* the usual case */
4419 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4420 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
4423 case SSL_ERROR_ZERO_RETURN:
4424 log_write(0, LOG_MAIN, "SSL channel closed on write");
4427 case SSL_ERROR_SYSCALL:
4428 if (ct_ctx || errno != ECONNRESET || !f.smtp_in_quit)
4429 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
4430 sender_fullhost ? sender_fullhost : US"<unknown>",
4432 else if (LOGGING(protocol_detail))
4433 log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
4434 " SMTP response and TLS close\n", sender_host_address);
4436 DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
4437 " client reset TCP before TLS close\n", sender_host_address);
4441 log_write(0, LOG_MAIN, "SSL_write error %d", error);
4452 ct_ctx client TLS context pointer, or NULL for the one global server context
4456 tls_shutdown_wr(void * ct_ctx)
4458 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4459 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4460 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4463 if (*fdp < 0) return; /* TLS was not active */
4465 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4467 HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
4468 rc = SSL_shutdown(*sslp);
4469 if (rc < 0) DEBUG(D_tls)
4471 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4472 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4476 /*************************************************
4477 * Close down a TLS session *
4478 *************************************************/
4480 /* This is also called from within a delivery subprocess forked from the
4481 daemon, to shut down the TLS library, without actually doing a shutdown (which
4482 would tamper with the SSL session in the parent process).
4485 ct_ctx client TLS context pointer, or NULL for the one global server context
4486 do_shutdown 0 no data-flush or TLS close-alert
4487 1 if TLS close-alert is to be sent,
4488 2 if also response to be waited for
4492 Used by both server-side and client-side TLS.
4496 tls_close(void * ct_ctx, int do_shutdown)
4498 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
4499 SSL ** sslp = o_ctx ? &o_ctx->ssl : (SSL **) &state_server.lib_state.lib_ssl;
4500 int * fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
4502 if (*fdp < 0) return; /* TLS was not active */
4507 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
4508 do_shutdown > 1 ? " (with response-wait)" : "");
4510 tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
4512 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
4516 rc = SSL_shutdown(*sslp); /* wait for response */
4520 if (rc < 0) DEBUG(D_tls)
4522 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4523 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
4527 if (!o_ctx) /* server side */
4529 #ifndef DISABLE_OCSP
4530 sk_X509_pop_free(state_server.verify_stack, X509_free);
4531 state_server.verify_stack = NULL;
4534 receive_getc = smtp_getc;
4535 receive_getbuf = smtp_getbuf;
4536 receive_get_cache = smtp_get_cache;
4537 receive_hasc = smtp_hasc;
4538 receive_ungetc = smtp_ungetc;
4539 receive_feof = smtp_feof;
4540 receive_ferror = smtp_ferror;
4541 tls_in.active.tls_ctx = NULL;
4543 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
4554 /*************************************************
4555 * Let tls_require_ciphers be checked at startup *
4556 *************************************************/
4558 /* The tls_require_ciphers option, if set, must be something which the
4561 Returns: NULL on success, or error message
4565 tls_validate_require_cipher(void)
4568 uschar *s, *expciphers, *err;
4572 if (!(tls_require_ciphers && *tls_require_ciphers))
4575 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
4577 return US"failed to expand tls_require_ciphers";
4579 if (!(expciphers && *expciphers))
4582 normalise_ciphers(&expciphers, tls_require_ciphers);
4585 if (lib_ctx_new(&ctx, NULL, &err) == OK)
4588 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
4590 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
4592 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
4593 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
4594 expciphers, ssl_errstring);
4605 /*************************************************
4606 * Report the library versions. *
4607 *************************************************/
4609 /* There have historically been some issues with binary compatibility in
4610 OpenSSL libraries; if Exim (like many other applications) is built against
4611 one version of OpenSSL but the run-time linker picks up another version,
4612 it can result in serious failures, including crashing with a SIGSEGV. So
4613 report the version found by the compiler and the run-time version.
4615 Note: some OS vendors backport security fixes without changing the version
4616 number/string, and the version date remains unchanged. The _build_ date
4617 will change, so we can more usefully assist with version diagnosis by also
4618 reporting the build date.
4620 Arguments: a FILE* to print the results to
4625 tls_version_report(FILE *f)
4627 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
4630 OPENSSL_VERSION_TEXT,
4631 SSLeay_version(SSLEAY_VERSION),
4632 SSLeay_version(SSLEAY_BUILT_ON));
4633 /* third line is 38 characters for the %s and the line is 73 chars long;
4634 the OpenSSL output includes a "built on: " prefix already. */
4640 /*************************************************
4641 * Random number generation *
4642 *************************************************/
4644 /* Pseudo-random number generation. The result is not expected to be
4645 cryptographically strong but not so weak that someone will shoot themselves
4646 in the foot using it as a nonce in input in some email header scheme or
4647 whatever weirdness they'll twist this into. The result should handle fork()
4648 and avoid repeating sequences. OpenSSL handles that for us.
4652 Returns a random number in range [0, max-1]
4656 vaguely_random_number(int max)
4660 static pid_t pidlast = 0;
4662 uschar smallbuf[sizeof(r)];
4668 if (pidnow != pidlast)
4670 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
4671 is unique for each thread", this doesn't apparently apply across processes,
4672 so our own warning from vaguely_random_number_fallback() applies here too.
4673 Fix per PostgreSQL. */
4679 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
4683 gettimeofday(&r.tv, NULL);
4686 RAND_seed(US (&r), sizeof(r));
4688 /* We're after pseudo-random, not random; if we still don't have enough data
4689 in the internal PRNG then our options are limited. We could sleep and hope
4690 for entropy to come along (prayer technique) but if the system is so depleted
4691 in the first place then something is likely to just keep taking it. Instead,
4692 we'll just take whatever little bit of pseudo-random we can still manage to
4695 needed_len = sizeof(r);
4696 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
4697 asked for a number less than 10. */
4698 for (r = max, i = 0; r; ++i)
4704 #ifdef EXIM_HAVE_RAND_PSEUDO
4705 /* We do not care if crypto-strong */
4706 i = RAND_pseudo_bytes(smallbuf, needed_len);
4708 i = RAND_bytes(smallbuf, needed_len);
4714 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
4715 return vaguely_random_number_fallback(max);
4719 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
4722 /* We don't particularly care about weighted results; if someone wants
4723 smooth distribution and cares enough then they should submit a patch then. */
4730 /*************************************************
4731 * OpenSSL option parse *
4732 *************************************************/
4734 /* Parse one option for tls_openssl_options_parse below
4737 name one option name
4738 value place to store a value for it
4739 Returns success or failure in parsing
4745 tls_openssl_one_option_parse(uschar *name, long *value)
4748 int last = exim_openssl_options_size;
4749 while (last > first)
4751 int middle = (first + last)/2;
4752 int c = Ustrcmp(name, exim_openssl_options[middle].name);
4755 *value = exim_openssl_options[middle].value;
4769 /*************************************************
4770 * OpenSSL option parsing logic *
4771 *************************************************/
4773 /* OpenSSL has a number of compatibility options which an administrator might
4774 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
4775 we look like log_selector.
4778 option_spec the administrator-supplied string of options
4779 results ptr to long storage for the options bitmap
4780 Returns success or failure
4784 tls_openssl_options_parse(uschar *option_spec, long *results)
4787 uschar * exp, * end;
4788 BOOL adding, item_parsed;
4790 /* Server: send no (<= TLS1.2) session tickets */
4791 result = SSL_OP_NO_TICKET;
4793 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
4794 from default because it increases BEAST susceptibility. */
4795 #ifdef SSL_OP_NO_SSLv2
4796 result |= SSL_OP_NO_SSLv2;
4798 #ifdef SSL_OP_NO_SSLv3
4799 result |= SSL_OP_NO_SSLv3;
4801 #ifdef SSL_OP_SINGLE_DH_USE
4802 result |= SSL_OP_SINGLE_DH_USE;
4804 #ifdef SSL_OP_NO_RENEGOTIATION
4805 result |= SSL_OP_NO_RENEGOTIATION;
4814 if (!expand_check(option_spec, US"openssl_options", &exp, &end))
4817 for (uschar * s = exp; *s; /**/)
4819 while (isspace(*s)) ++s;
4822 if (*s != '+' && *s != '-')
4824 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
4825 "+ or - expected but found \"%s\"\n", s);
4828 adding = *s++ == '+';
4829 for (end = s; *end && !isspace(*end); ) end++;
4830 item_parsed = tls_openssl_one_option_parse(string_copyn(s, end-s), &item);
4833 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
4836 DEBUG(D_tls) debug_printf("openssl option, %s %08lx: %08lx (%s)\n",
4837 adding ? "adding to " : "removing from", result, item, s);
4849 #endif /*!MACRO_PREDEF*/
4852 /* End of tls-openssl.c */